Quote Originally Posted by Ajani

1) Upgrading Cables makes a sonic difference - IMO yes, but not a major one. Some very cheap and basic initial upgrades to thick, properly shielded cables will solve all my cable needs. Anything more expensive seems more about high profit margins than value for money to me.

2) Vibration control devices (feet, heavy rocks, platforms/whatever) improve sound quality - IMO, probably - just listen to how bad a skipped record or CD sounds and it should be clear that vibration can affect sound... however, I think most products are sufficiently heavy, that unless you live on a train vibration probably isn't that big a deal.

3) Upgrading power cords/filtering power supplies improve sound - Theoretically yes... Based on how bad simple magnetic interference can make a tv image look, I can imagine a similar effect with sound quality... But I question how many of us live in areas with truly poor electrical signals/interference and also whether the standard shielded power cables of our components aren't sufficient...

4) Source makes a great difference in sound - Yes... but I think the biggest difference is the quality of the recording and not the 'quality' of the CD player. I've heard definite differences between CD players/lossless computer audio and DVD players... but truth is that none of it was significant to me apart from in painstaking direct comparisons... But a poor quality recording tends to be obvious.

5) Bi-wiring your speakers improves sound - I doubt it. So far I've been unable to tell the difference between single and bi-wired speakers even in direct comparison.
To start off, I am of course NOT in the leagues of most if not all of the others have answered, but I will provide input for people on a more amateur level.

1. Well, yes. I heard a pretty significant difference switching from the el-cheapo 18 gauge wire I had to the god-knows-how-thick solid copper extension cord I stripped and used. Great sound surprisingly, and cheap too.

2. Never had a problem with it in my own experience. My speakers are sitting on some thick hockey socks which I folded up. They do a grand job of isolating them from my speaker stands.

3. Wouldn't know. I don't even think my set-up is good enough to show a sonic difference between 'clean' power and 'dirty' power.

4. Yes, yes and yes. Especially from really cheap stuff to mid-priced (mid priced being a couple hundred) stuff. My marantz made a great change to my system. Had been using an el-cheapo DVD player as a source...yeah. Big change. But the curve levels off after a certain point I think. Once you get into the thousands the difference becomes so minute only the best ears can hear the difference.

5. Never bi-wired so I wouldn't know. Theoretically it would, but sonically, who knows. It may even just be the placebo effect.