Pros: Just about everything
Cons: Chassis, is the only thing I could complain about.
I actually decided to buy the Apex Peak/Volcano, I do not regret purchasing this amplifier even though a loaner program was available for sometime, although I don't know if it was still going on when I bought the amp.
For headphones I have the Audez'e LCD-2 and Ultrasone Edition 10. I only used the ED10 very briefly as I actually prefer the sound of the LCD-2 to the ED10s. So now that is out of the way, I am using a Q-Audio headphone cable, Yulong D100, and Onkyo ND-S1. I didn't even bother with using the stock tube the amplifier came with as I have a pretty strong NOS collection of 6SN7s. I ran the amplifier with a Marconi Osram B65 for about 50 hours and switched over to Mullard ECC32 and have about 50 hours on this arrangement.
I generally listen to a lot of rock. One of my favorite albums to listen to on different amplifiers to see their chops is Eric Clapton's One More Car, One More Rider. So with the Mullard ECC32, I find that I like this sound the most. The amplifier was meant to play the electric guitar, when Clapton goes into any of his guitar solos, the guitar just sounds so right through this amplifier. The amplifier is pretty much as advertised, a blank slate for you to roll your favorite tube in and listen. I like my sound a little bit on the warm/lush side of neutral and so I tend to pick the Mullard ECC32 over the TSRP. All my favorite characteristics of the ECC32 come through quite nicely. I find that this amplifier plays the entire audible spectrum extremely well. The bass is strong, tight, and well blended with the midrange. The mid range of this amplifier is probably my favorite part. The electric guitar just sings on this amplifier, but in general I find it plays pianos, saxes, and really presents what is available in your setup. This amp has actually made me decide to upgrade my DAC once and for all. BTW I'll say as far as digital sources go, I'm not one of those types that really believes in the whole spend as much as you can on sources, I come from the school of though that is spend your money on the transducers to get to where you need to go, then analog second (amps, preamps, analog section of DAC, etc.), third digital as seen by my reluctance to get more expensive sources than the D100 and PS Audio DLIII.
My other favorite type of music to listen to is female vocalists. I really enjoy listening to Natalie Merchant, as I find that her music from the mid 90s on to be such great music to listen to. In any even her voice really just sounds perfect to me with this amplifier. I've heard her voice a number of different ways now and I just feel like this is about as good as it gets when it comes to amplifiers and in particular with the LCD-2s. But knowing that more people in the high end communities will use Diana Krall's voice as a reference point as opposed to Natalie's, I'll just say she sounds great to me with this amp as well, but I have less to compare it to so I won't go so far as to call it perfection, well because I don't listen to her quite as much.
In general I find this amplifier as having accomplished what I consider to be the ultimate in amplifier architecture. The vacuum tube being an inherent voltage device and the transistor well suited for current sourcing. To me this amp has just the right amount of warmth to really give the most pleasurable listening experience, but the deep well defined bass that the best solid state amplifiers can give, which can be at times lost in an all tube amplifier. The treble of this amplifier is nothing short of excellent. I love the way it presents cymbals being played from a drum set. In general, this amplifier has all the detail that I care for, great tonal balance, blends the entire frequency spectrum very well. I have never really found any headphones that terribly impressed me with imaging/sound stage, and I really don't attribute this to the amplifier, although my comment here would be that it is amongst the best I've heard the LCD-2 do.
Finally, TTVJ and specifically Todd, is one of best people I have had to deal with in this particular industry so far. So I certainly recommend this amplifier to anyone looking for a great amp to use with the LCD-2. I actually think that if you happen to like th ED.10s you will also like this amplifier for them as well, although who knows as I am not one who considers them my favorite headphones so I am not really sure what those folks are looking for. Anyways, enjoy and I hope this helps anyone interested in purchasing this amplifier.
Edit: As a clarification, I don't think the chassis is bad, I just think its probably the only thing I wasn't floored by. Its an otherwise very solid construction.