Class A, B, AB.. explained and Amp Brand results

[OzzieAudiophile]

Hello.

The following link provides a technical explaination of each Class type.

Perhaps good food for thought, don't use the following information to necessarily
stay away from specific brands/models. This is "purely" for information purposes
only.

http://en.wikipedia.org/wiki/Electronic_amplifier

Just taking a look at the last few owners manuals that I've downloaded from the
official websites here are the Class Types for brands of amps/receivers :

Balanced Technology : does not mention in the manuals
Boulder 2060 : Class A (weights 332 pounds, shipped !!!)
Bursonaudio PI-100 : Class AB
Cambridge Audio Azure Series (840 etc) : Class A and Class AB
Denon : Class B (from manual of top of the range receiver)
Integra : does not mention in the manuals
Marantz : does not mention in the manuals
McIntosh : does not mention in the manuals
NAD Master Series Integrated Amp : Class A
NAIM : Class B
Parasound A21 : Class A and Class AB
Plinius P10 : Class AB
Primare : Class B
Rotel : One series confirmed as Class D
Yamaha : Class B (took a look at many manuals, all Class B)

It is highly recommended to read the full owners manual as other features within
the components should be considered and not necessarily take the class type
as the main reason to buy or not buy the component.

It is also recommended to read as many reviews of the products. As stated,
the above information is purely for information purposes only.

I hope you find the above information useful.

[Feanor]

Thanks for your research, OA. It's interesting to see the claims of manufacturers.

Quite a few imply a greater degree of Class A operation than is really accurate. In the first place, Class A operation is common among preamps or the first stage of amplification.So for integrateds, the manufacturer will proclaim Class A, but on close inspection you see this really only applies to the preamp circuitry. By the same token they claim "A/AB" operation where the pure "A" part is only the front end or first amplification stage.

Apart from switching amps, i.e. Class D and proprietary variants, almost all powerful amps are Class AB, that is, Class A at low power levels to avoid "notch" distortion, but Class B and higher levels. Pure Class A amps are rare and tend to be lower powered. Pure Class A wastes a low power which is dissipated as heat, the more powerful the amp, the more waste and heat.

Sophisticated ciruitry has be developed, e.g. by Nelson Pass, to automatically adjust the Class A "bias", (point beyond which the amps goes to Class B operation). Thus as low levels volumes the bias is set just high enough to ensure continuous Class A operation but not produce excessive heat; as volume increase, the bias is increased to the same effect.

A minor issue I have with my Monarchy SM-70 Pro amps is the degree of Class A operation and also the amount of feedback. At one time this model was advertised as "Class A, zero feedback". I addressed the Class A question to the principal, C.C. Poon, who was quite coy on the subject, he replied that the amp operates in Class A mode "most of the time". In fact these amps run quite hot. However they are no longer advertized as "Class A". And by the way, feedback is used in the front end circuitry though not in the final stage nor globally, (back-to-front).

[oaqm]

There is no way on God's grey earth the Denon, Naim, Primare, and Yamaha are straight Class B amps.

They would sound like old AM hand held transistor radios if they were.

I have a 20 ounce ice-cold coca cola that says they are all A-B amps.

[elapsed]

There is no way on God's grey earth the Denon, Naim, Primare, and Yamaha are straight Class B amps.

They would sound like old AM hand held transistor radios if they were.

I have a 20 ounce ice-cold coca cola that says they are all A-B amps.
Here's a posting from 1998 from Julian Vereker (1945-2000), founder of Naim. I can assure you my Naim stack doesn't sound like an old AM hand held transistor radio. But I'll take that 20 ounce ice-cold coca cola. ;)


Date: March 29, 1998 03:55 AM
Author: julian vereker
Subject: Bias

All Naim power amps are class B and they have as low a bias as we
can manage, just a few milliamps.

There are two reasons for doing this, in order to make a good
push/pull power amp, the two halves need to match very closely
since there is only one common feedback loop - this applies whatever
the 'class' of the amp. If one achieves this degree of precision
then one only needs a very small bias current.

Also it is extremely wasteful of resources making class A power
amps, since they use large amounts of electricity even when they
are not playing music, this means the waste heat has to be dissipated
into the atmosphere without overheating the components and thus
shortening their lives, which implies large heatsinks, big heavy
and expensive in terms of resources pieces of equipment.

There are quite a few power amps about, that are called class A
for marketing reasons, but are in fact to all intents and purposes,
class B. (Save the planet - buy class B).

julian

[oaqm]

Naims are not pure Class B.

"one only needs a very small bias current"

That's the definition of an AB amplifier.

[elapsed]

That's the definition of an AB amplifier.
Touché.. ;)

[OzzieAudiophile]

Order , ORDER (bang bang bang, with gavel) haha.

Seriously, I have noticed that models which are AV receivers are more
class B than class A, or AB. The nicer amps are either A or AB, or
combination of A and AB. Well, I wouldn't use what class it is as
the most important factor in considering to buy to dismiss a specific
brand. How it is built, the reputation, reviews, cost, have to be
considered.

If you're unfortunate like myself, the choices are a bit thinner than
the Europe and USA. Still, the amp/receiver MUST be able to drive
your speakers efficiently and sufficiently, having much reserve power
does make a difference also.

It appears that Class AB and/or a combination of A and AB seem to
either have the best of both worlds, and best value for money.

[Ajani]

Well, I wouldn't use what class it is as
the most important factor in considering to buy to dismiss a specific
brand. How it is built, the reputation, reviews, cost, have to be
considered.

:idea:

Ummm... and how it sounds, might be also be a consideration.....

:ciappa:

[Feanor]

For me, solid state design is eputomized by Pass Labs XA.5 amplifiers which combine high-power, ultra-low feed back, balanced, almost exclusively Class A operation. They sound great by all reports. And, damn, they look gorgeous.

Read some not-too technical discussion of the XA.5 design here (http://www.passlabs.com/pdf/product%20lit/x.5-xa.5-amps.pdf).
...

[OzzieAudiophile]

Ajani - if I had to include every obvious aspect of an amp, I'd be listing them all until
the end of time.

I thought we were not dealing with 5 year old kids, and had to be overly obvious.

[E-Stat]

Seriously, I have noticed that models which are AV receivers are more class B than class A, or AB.
I'm with oaqm about this. I think you don't really understand what a true class B amp would be like. Here is a design that only works well at full output. At anything less (which would be 99% of all listening), the distortion levels would skyrocket. The only integrated amp I've owned was an AR Integrated back in 1972 which was a class B design. Resolution went totally out the window at low levels. Even the least expensive components these days are AB designs.

Like balanced vs. unbalanced connections, you really cannot make any sweeping judgments on the output design alone. There is no one way to implement a class AB amp either. The better ones are not only biased further into class A, but they are simpler designs with little or no global feedback. They also have far larger power supplies. Whereas my 1981 Threshold Stasis 3 (100 watts/channel into 8 ohms) has 63 joules of storage (50,000 uf / 50 v), my VTL mono amps have 250 joules of storage each. The big brother VTL Sigfried amps have nearly 800 joules each. You just don't see that data in common specifications. Here's the formula if you know the total capacitance and rail voltage (not capacitor rating): J=CV(squared)/2. Thats capacitance in farads times voltage squared divided by 2. HT receivers have tiny power supplies by comparison.

rw

[OzzieAudiophile]

Thanks for the explaination E-Stat.

Well at least in Australia, the more expensive amps with the good reputation are more ClassA than not. Assuming one can afford it, it is better in general to purchase a Class A amp, than any other class ? I have not seen much bad reviews on Class A amps.

A lot of Class A (at least in Australia) are in a price bracket way above much else.

I'm still auditioning other amps at the moment, and out of my short list half of them
are Class A, the rest are not. I found out that McIntosh are Class A, but most of your
feedback has been negative, in terms of their design.

EG.

[Feanor]

Thanks for the explaination E-Stat.
....

I'm still auditioning other amps at the moment, and out of my short list half of them
are Class A, the rest are not. I found out that McIntosh are Class A, but most of your
feedback has been negative, in terms of their design.

EG.

OA, I didn't know that McIntosh made any Class A power amps. I curious to know whether that is all or just some models. Can you provide links?

Here is an example of a current production, high quality, pure Class A amp, the Accuphase A-60 (http://www.accuphase.com/model/pdf/a-60_e.pdf). I'd love one of these. It is only 60 watts per channel at 8 ohms yet weighs 100 lbs. (It does do 480 wpc @ 1 ohm! :eek6: )

[E-Stat]

Assuming one can afford it, it is better in general to purchase a Class A amp, than any other class ? I have not seen much bad reviews on Class A amps.
Generally speaking, yes but not necessarily. You need to consider the speakers. While it would be very nice to have a pair of 200 watt Pass Labs XA200.5s, I'd rather have the higher output of an excellent AB design like the VTL Siegfried for my speakers (and $40+k). In my vintage system, however, I always run the Threshold Stasis at levels where the output stage is running class A. Driven directly by a tube output DAC at that.


I found out that McIntosh are Class A, but most of your feedback has been negative, in terms of their design.
NONE of their amplifier designs are class A. Never have been. They are plain Jane dual darlington, complex circuit designs with autoformers. True class A designs are necessarily heavier for a given output and require far larger heatsinks. A 100 watt mono Pass Labs XA100.5 amp weighs more than a 250 watt per channel stereo McIntosh amp.

rw

[basite]

Generally speaking, yes but not necessarily. You need to consider the speakers. While it would be very nice to have a pair of 200 watt Pass Labs XA200.5s, I'd rather have the higher output of an excellent AB design like the VTL Siegfried for my speakers (and $40+k). In my vintage system, however, I always run the Threshold Stasis at levels where the output stage is running class A. Driven directly by a tube output DAC at that.

I've heard quite some class A designs (including those from Threshold) that sound extremely boring, flat & thin to me. and I found many class A/B gear that outperformed their class A opponents (in their price class...)


NONE of their amplifier designs are class A. Never have been. They are plain Jane dual darlington, complex circuit designs with autoformers. True class A designs are necessarily heavier for a given output and require far larger heatsinks. A 100 watt mono Pass Labs XA100.5 amp weighs more than a 250 watt per channel stereo McIntosh amp.

rw

Mc's indeed are class A/B (albeit more biased to class A than class B)

and their complex circuit designs with those oh so evil (not) autoformers do sound better to me than the pass labs IMO...

[E-Stat]

I've heard quite some class A designs (including those from Threshold) that sound extremely boring, flat & thin to me.
Agreed. That was the point I was making. Krell is not my cup of tea either. I remember meeting Dan D'Agostino when he was the rep for Dayton-Wright and Dunlap-Clarke back in the 70s. Given that virtually all small signal amplification found in line stages and preamps is run class A, there is a wide range of outcomes. Similarly, "ultra low distortion" amps from Halcro sound too lean and harmonically undernourished to these ears.


...and their complex circuit designs with those oh so evil (not) autoformers do sound better to me than the pass labs IMO...
One has to wonder, however, why it is that McIntosh alone has chosen that particular route.

rw

[OzzieAudiophile]

E-Stat : I am actually counting on that you're right about the McIntosh not being ClassA.
My supplier stated that new MA6500 is, however I'll get an answer directly from McIntosh.
If I do not get an answer from them, I'll scratch them off my list.

I have nearly scratched off Cambridge Audio from my list because of their slow response.
My enquiry was regarding specs, a 7 day non-response is not acceptable.

From all of the brands I have auditioned so far, none of the amps are extremely heavy.

There's the Boulder 20K amp that made my mouth water, it is 336 pounds shipped.
I found a link of the man delivering it. The box is about 2m by 2m, the actual amp is
bigger than a small kid. Now you won't need any anti-theft device. The amp itself
is anti-theft. Unless you're able to lift 252 pounds.

Due to a reality check, there's no way I'd be able to afford a 20K amp, or anything
above 6K for that matter. So regardless of all the tasty options of various amps,
I may be forced to get one of those lighter ones. I know most of the nice ones that I
can afford out there will be a suitable replacement for my Yamaha receiver. It will
need to power my Dyn Audio Contour 1.8 Mark II's 250 W 4 ohm speakers.
They definately need quite a bit of juice to feed them.

Believe me when I say that there is not a huge variety of first rate amps in my
part of Australia.

Basite - I would not take the constructive, but both positive and negative feedback
about McIntosh, also in regards to their designs. After auditioning that brand, plus
other brands, McIntosh does sound cleaner, greater detail than the others.
It's weighing up how much better sound you want to how much more are you
willing to pay for it. The phrase "diminishing returns" applies. I don't want to spend
too much money, then again I don't want to waste 1.5K, 2K, 3K etc for an amp
that I know I am not happy about.

I see that most of the heavier amps sit on the floor. So there is no way they can
exist in a cabinet ? My new cabinet does have a lot of space, worse case scenario,
I'd be willing to install a cooling system. It would be only for an amp, the other
components are most unlikely to overheat. Must go to show what quality build my
components must be haha.

EG.

[E-Stat]

E-Stat : I am actually counting on that you're right about the McIntosh not being ClassA.
My supplier stated that new MA6500 is, however I'll get an answer directly from McIntosh.
If I do not get an answer from them, I'll scratch them off my list.
First of all, I'm not necessarily trying to steer you away from getting Mac. It's just there are so many other competitive brands. Perhaps I'm just too blunt, but I've been in the audio world for more than thirty years. I worked at a hi-fi shop in the 70s, have two prominent audio reviewer friends and have been exposed to a wide range of gear. McIntosh remains the "Cadillac" of audio, but some folks prefer a BMW or Porsche.

As for the story on the 6500, all you need do is visit the McIntosh website. There you will not find any references to class A operation. No biggie. Look specifically at the 6500 page here. (http://mcintoshlabs.com/products/993.asp) Here's a 120/200 watt per channel (8/4 ohms) stereo amp that weighs 41 pounds and pulls 4 amps (480 watts) from the wall. It is impossible for that to be a Class A design. It would weigh as least four times as much and idle at something like 600 watts if it were. Look at any of their other amplifiers like the 6600 or the 7000. Or one of their mono blocks. I guess my only concern is that it seems your dealer (or at least that salesman) doesn't understand these basic facts.


I have nearly scratched off Cambridge Audio from my list because of their slow response.
My enquiry was regarding specs, a 7 day non-response is not acceptable.
You know, many of these companies are relatively small and just don't have that kind of marketing capability. Some audio companies don't take email for that very reason. I wouldn't fault the company for that reason.


Due to a reality check, there's no way I'd be able to afford a 20K amp, or anything above 6K for that matter. So regardless of all the tasty options of various amps,I may be forced to get one of those lighter ones.
And you should be able to get quite an incredible amp for that kind of change.


Believe me when I say that there is not a huge variety of first rate amps in my part of Australia.
It seems tough enough even here in the states because you may need to travel a bit, but I guess we're lucky overall with availability.


I see that most of the heavier amps sit on the floor.
Mono blocks can also be placed behind each speaker. I have mine on the floor atop some maple stands.

rw

[OzzieAudiophile]

E-Stat , cheers for the advice. I am taking it with great value. In case anyone is trying
to tell me I'm interested in it due to McIntosh's great looks, the very last reason I would
buy a component is because it looks nice.

I took some time to take a look at various options that I have so far, took a look at the
weight of each amp.

What is available so far in my area of Australia :
The following is in order from heaviest to lightest (of my options)

McIntosh MC402 Power Amp - 110.5 lbs (50.1 kg net) - 400 wpc - 10K ($90 /1 lb)
McIntosh MC252 Power Amp - 94.5 lbs (42.87 kg) - 250 wpc - 7K ($74.07/1 lb)
McIntosh MA6900 Integr Amp - 74.5 lbs (34kg) net 200 wpc 8K ($107.38 /1lb)
McIntosh MA6500 Integr Amp - 74.5 pounds (33.8 Kg) 250 wpc - 5.5K ($73.83 / 1lb)
Parasound A21 Power Amp - 60 lbs (27.3 ks) 250 wpc - 4.2 K ($70 / 1lb)
NAD Master Series M3 Int Amp - 25kg - 180 wpc (cts) 480 wpc (dynam) - 4.5K ($81/ 1lb)
Camb Audio 840A Power Amp - 48.2 lbs (21.8 kgs) - 200 wpc - 2.4K ($49.79/ 1lb)
McIntosh MA6300 Integr Amp - 37 lbs. (16.8kg) 160 wpc - 5K ($135 / 1lb)
Camb Audio Azur 840A Int Amp - 15 kgs 120 wpc - 2.2K ($66.67 / 1lb)
Plinius P10 Power Amp - 30 lbs (14 kgs) 200 wpc - 4.5K ($150 / 1lb)

These prices are worse than the local meat markets :)

All other choices exist in the USA and Europe :(

[audio amateur]

McIntosh remains the "Cadillac" of audio, but some folks prefer a BMW or Porsche.
Careful there, you might make Bert regret his purchase:cornut: haha
Other than that your posts are always very informative thanks alot

[E-Stat]

E-Stat , cheers for the advice. I am taking it with great value.
Ideally, you need to take each of the contenders home and listen to your favorite music through them. At high levels. At low levels. There is much to speaker compatibility that you just cannot determine by looking at the usual collection of specifications.

Failing that, Mac has an advantage with its superlative resale value. You could always buy one and try it out. If you're not happy, then sell and try again.

rw

[Feanor]

....

What is available so far in my area of Australia :
The following is in order from heaviest to lightest (of my options)

McIntosh MC402 Power Amp - 110.5 lbs (50.1 kg net) - 400 wpc - 10K ($90 /1 lb)
McIntosh MC252 Power Amp - 94.5 lbs (42.87 kg) - 250 wpc - 7K ($74.07/1 lb)
McIntosh MA6900 Integr Amp - 74.5 lbs (34kg) net 200 wpc 8K ($107.38 /1lb)
McIntosh MA6500 Integr Amp - 74.5 pounds (33.8 Kg) 250 wpc - 5.5K ($73.83 / 1lb)
Parasound A21 Power Amp - 60 lbs (27.3 ks) 250 wpc - 4.2 K ($70 / 1lb)
NAD Master Series M3 Int Amp - 25kg - 180 wpc (cts) 480 wpc (dynam) - 4.5K ($81/ 1lb)
Camb Audio 840A Power Amp - 48.2 lbs (21.8 kgs) - 200 wpc - 2.4K ($49.79/ 1lb)
McIntosh MA6300 Integr Amp - 37 lbs. (16.8kg) 160 wpc - 5K ($135 / 1lb)
Camb Audio Azur 840A Int Amp - 15 kgs 120 wpc - 2.2K ($66.67 / 1lb)
Plinius P10 Power Amp - 30 lbs (14 kgs) 200 wpc - 4.5K ($150 / 1lb)

These prices are worse than the local meat markets :)

All other choices exist in the USA and Europe :(

OA, since you're considering both power and integrated amps in this mix, what would you use for a preamp if you when for one of these power amps?

The prices seem ridiculous but are they Aus$? For what it's worth, of this lot I'd probably go for the Parasound A21, (based on reputation, not audition), as the best combination of performance & value. My personal second and third, in that they're integrated, would be the NAD M3 and McIntosh MA6500. The Mac power amps seem just too over-priced.

[Feanor]

Ideally, you need to take each of the contenders home and listen to your favorite music through them. At high levels. At low levels. There is much to speaker compatibility that you just cannot determine by looking at the usual collection of specifications.

Failing that, Mac has an advantage with its superlative resale value. You could always buy one and try it out. If you're not happy, then sell and try again.

rw

Check OA's shipping costs. :shocked:

[basite]

Careful there, you might make Bert regret his purchase:cornut: haha
Other than that your posts are always very informative thanks alot


never :)

his posts are very informative though :D

oh, ozzie, your dealer is wrong, the Mc's are class A/B designs. All of them.
and don't just scratch brands of your list, just because they aren't responding to you mail within one week. they probably get countless mails each day, and only few people to read them, so it can take a while sometimes...

Keep them spinning,
Bert.

[OzzieAudiophile]

Feanor : yes the prices I quoted are Australian ones. I am sure all you guys from
the US need to do is mulitply the prices by 0.93 (or depends on what day it is). I would
be more than sure the prices you would have to pay is far less than 93%.

I have auditioned all except the Cambridge 840 series.

I will have to audtion them at home, and if I am not given that option, I won't consider it.

Of course they would sound around only 70 to 90% as soon as they will be "after" they
are broken in. I'll have to consider that.

Cambridge Audio sounds way too good to be true price wise. McIntosh sound way
too pricey for my budget lol. Grrr I will pay what it costs if I am 100% happy with the
sound.

The same 3 CDs were all auditioned, and the same tracks to limit differences.
1. Andrea Bocelli - Andrea (SACD/hybrid)
2. Jeff Wayne's The War of the Worlds (SACD/hybrid)
3. Hayley Westenra - Oddysey (test of the highs)

The above three sound the best out of my entire music collection.

From what I have acutally auditioned, here is the order of how much I was impressed :

1. McIntosh 2 x MC1201 monoblock(1200 w), double-balanced 78 Kg each
= 29K each, total system plus B&W 1000 W speakers, plus player etc - 90K.
Could hear at least 2x as many voices, instruments. Never heard anything better. Never
thought music could sound so wonderful. I found out the price, AFTER I auditioned it. No
price tags on the units.

2. Plinius P10 + CD player + preamp (total retail 21K) - cannot handle the highs or lows,
mid range is fine, at least in the shop. Perhaps speakers are to blame.

3. NAD Master Series Universal player for DVD, non Universal SACD/CD only for SACD.
Pretty good, nothing grabbed me, not beyond my expectations, not for a 9K system.

4. Parasound - the speakers were also Dynaudio so the only 4ohms, 16K Confidence
pair. The setup and acoustics was quite poor and that is being polite. Lack of bass,
sounded quite bright, no instrument reached out and grabbed you. Singing voices
was good. It appeared to be a $10 cable hookup job.

Of the 3 shops that supply the 4 brands, I must buy the units outright to "audition" it.
I cannot take it home. The last one I must place a 10-15% deposit to lend it (Plinius),
which I can accept and understand, a shop needs to cover their costs. I will try to
negotiate new options, there is no way I will buy a unit I cannot test at home first.

I would probably be 80% sure whatever I buy I will not need to return it, but the fact
that I cannot take it home to test without paying full price is a sign of bad service.
I am not related to the poor sods in the past who returned goods in poor condition, and
shouldn't be made to suffer for that.

I don't intend to buy a unit just to sell it straight away. It's a waste of my money, time,
and effort. It would certainly kill off any future business I would do with the shop. I
certainly hope you guys are not in the same bad rockety boat as I am, or is service/
business in the US/Europe shops the same as in Australia ?

Oh and because 3 of the 4 shops is admitted that they are "small", any other model
that I'm interested in which they don't have, I have to buy it outright to test it. Bringing
in a unit just to audition is not allowed.

As much as I'd like to take anyone's word for it, "yeah it's good you'll love this", 3 to 10K
is simply not money I can afford to throw away on blind faith. All the manuals, statistics,
reviews mean nothing to me.

For example, I have read over the last 2 years in what's hifi that the Cyrus players and
brand are the go, the ones that have won this award, that award, definately worth a try.
Well eventually I found a shop which managed to get the Cyrus players in. Extremely
heavy for half the size of a suitcase, heavier than most amps I listed in my previous
post on this thread !!. When I finally auditioned Cyrus, it did not justify it's price, or any
price for that matter. It's the same shop that BANG, these are the speakers I'm going
to get (the DynAudio 1.8 Mark IIs). So I cannot blame poor setup or placement of
speakers for my bad luck auditioning stuff there.

You're completely right E-Stat. I really must audition the unit at home, and with my
Dynaudio 1.8's. I must admit I'm not so impressed with the speakers in the shops.
I may be just too used to them by now, the detail the highs, midrange, the singing
voices, the bass, absolutely incredible. Like I said in other posts, I have just about
lost count how many people have come to my house and told me how much they
loved my speakers, or wanted to get a pair themselves.

Before I get in ppl's bad books, I know for a fact that most of you guys would have
much better speakers. Again, maybe 6-8 high-end brands of each type, that's all we get.

[E-Stat]

Check OA's shipping costs. :shocked:
I think his calculation was a simple purchase price / weight. Reselling locally shouldn't require massive freight amounts.

rw

[E-Stat]

Careful there, you might make Bert regret his purchase:cornut: haha
Other than that your posts are always very informative thanks alot
Nah, I think he's quite happy for now. If he ends up like I was at his age, however, I suspect over time that will change. He'll get separates. I went through lots of gear until I was 21 or so - where by that time I had a wide exposure to what was available and a better understanding of my own priorities.

To tell you the truth, there is so much more really good gear available today than thirty years ago. Folks talk about the death of two channel and the high end, but from a consumer's standpoint, I just don't see that yet.

rw

[Feanor]

I think his calculation was a simple purchase price / weight. Reselling locally shouldn't require massive freight amounts.

rw

Yes, I guess that's what he meant. Surely this is pretty specious measure though. At least it's meaningless across amps of different classes, e.g. Class A very heavy; Class AB in the middle; Class D very light, especially where a switching power supply is used.

As I recall, Odessey still talks about $ / lb, implying that their stuff is better values for being heavy for the buck.