Well, I have a BAT in the house. I installed the tubes and have about 40 minutes of listening so far.

Here are my son's comments- "It sounds more high end than the Pass. It has a blacker back ground. The sound is more holographic and there is more spacing between the instruments. Everything sounds more life like. Things sound crisper. There is more detail. It is more musical and there is more front to back depth. It has a more forward sound. Treble is more prominent and better. The sound stage is not as wide. Bass does not have as much slam but is seems tighter. The midrange is deeper and better. It does not sound too tubey. Vocals sound like they are in the room with you"

Those were my son's impressions and I have to agree with everything. I might add that the sound is a little darker. There is a little less air than the Pass but I think that is because the music has more texture and depth. There is more emotion to the music. The attack on guitar and piano is much better, almost like my Parasound was but smoother. Guitar and piano sounds more natural as all the instruments do. Piano has much better decay as well. Vocals are much better and more realistic. The back ground is much quieter than the Pass and there is definitely more detail and resolution. In addition, there is much less sibilance on sibilant recordings.

Things that I don't like are the loss of bass slam and overall drop in bass. It is not thin or weak by any means, it is just that I got use to the bass with the Pass which sometimes could be over powering. Part of the problem is that there is a loss in gain with the BAT and part of it is due to the fact that I am using a single ended cable from my DAC with an XLR adapter, the same goes for my sub. I think that there is either a 3 or 6db loss in volume with the adapters. On the Pass I never had to turn the volume above 18 but on the BAT I have to turn it up to 80-105db with the max at 140. Even at 140 it does not sound as loud as the Pass. Unfortunately the BAT does not have a gain boost setting like the Pass. The only other things that I don't like are the slight loss in air and sound stage as well as the slightly more forward presentation. I will have to change the settings on my sub to compensate for the bass difference. I may have to bump the cross over up about 5hz and increase the volume a smidge.

I am sure some things will get better as the tubes break in. I was really planning on letting the tubes break in for about 10 hours before listening but you know how that goes. I will post updates as things begin to change. I won't make a decision until I have about 30-40 hours on the tubes.

In a previous post I said that I did not think that there would be a big improvement in the sound between the Pass and the BAT. I think that was an over statement as the 2 preamps are night and day different with the BAT having the huge edge in detail, resolution, musicality, emotion, texture and blackness to the background.