Had a great time today listening to my HD 800's with this amp, especially with the new Sylvania tubes. 6BX7GT, chrome dome top mica, matched traces and internal structure, but different date codes. I started Glenn Gould's Goldberg Variations, an old recording but a classic. The hiss of the old mics don't bother me through this amp, unlike some amps where it becomes really fatiguing. Also, the microdetail like sympathetic resonance on the other piano strings and room echos were not obscured by the amp. I then queued up the funeral march from my Decca recording of Nabucco to test the soundstage. Holy crap, the soundstage is wide, this song makes it really feel like it stretches more than 10 meters in both directions. It wasn't the deepest soundstages I've heard, but it's by no means flat or two dimensional. Room echoes were also well recreated. I then listened to The Modern Jazz Quartet, live at Carnegie Hall from MFSL. Bass extension was great, and it's not rolled off like some amps with lower-quality output transformers. Whoever makes Dennis' transformers knows their stuff. I tested the highs with EDM, and that gave me a horrible headache. Suffice to say, extension on the high end is good, but that's ultimately a bad thing for the HD 800's. That also ended the serious listening session, might do some comparisons with other amps I have on hand later. EDIT - Quick 'n dirty comparison with a Liquid Crimson Turned on my Cavalli Liquid Crimson and gave that a listen with the same tracks, switching the headphones between them. The mains differences I notic ed is that the Bass on the Cavalli is faster, and the Highs are clearer. Things like cymbals sound more natural on the Cavalli, like there's a bit better attack and decay. Bass is clearer and has faster decay, but not by much. These differences are probably caused by the very different topologies of the amps, I know the LC has no output transformers and uses MOSFETs for the input stage.