Was originally planning on rolling TS 7236 + RCA 5693, but then my 2nd GEC 6as7g as well as ef80 adaptors arrived in the morning and I couldnt resist... In short, wow, that's why everyone worships this tube. All my listening today was on HD800. GEC 6AS7G + TELEFUNKEN EF800 Everything about the GEC is just right. The first thing that hit me was the superior micro-detailing, soundstage+imaging and the layering. Bass extends so well, I've never heard my HD800 reproduce such good sub-bass. Treble is equally well extended, very smooth and very even. Mids, especially lower mids, have perfect amount of weight. If I had to complain about any one thing, it would simply be that it is not as relaxing as a warmer tube; this is truly analytical but still, for my tastes, full of musicality and most importantly, renders the tone of everything just right- not too bright/shrill, and definitely not too dark. Celli+double bass have never sounded so good; their reverb in Carnegie Hall is now accurately captured beyond the initial attack, and bass pizzicato now seems to extend almost to the other end of the stage, can almost feel the vibrations on both sides of the headphones. Horns+ trombones+contrabassoon whips and entries in Bernstein's rec of Shosta 5 are the most brutal I've ever heard them, exactly the sound I imagined when I first saw the score. The microdetails (by extension, the transients too) are unparalleled in orchestral music; I can discern the individual bowstrokes of ppp violin tremelos, the crunch of the stick hitting the strings in the weighty sections that deliver the quintessential shostakovich sound which I've only ever heard reproduced when actually playing in an orchestra, and I can make out the individual attacks of each violinist in col legno sections. I can hear the individual keys being pressed and air passing through them on the saxophone upon its entry in Shafran's 2nd movement of Kabalevsky 2. The layering (and i guess almost synonymous with separation as well?) is also something I've missed out on until i heard this combination. Orchestral textures are so well separated yet still musically coherent. The sound actually is slightly congested at 50% of regular listening volumes, but above that it opens up, as does the soundstage. Soundstage is widest and deepest I've heard so far. This supreme layering made me laugh during G Gould's 1981 goldberg variations; I can't imagine the piece any other way now, his singing is so well entwined with the delicate keyboard playing(i can hear the individual fingers hitting the keys even in the densest moments of Bach's writing). EF800's did not impress off the bat, but I now appreciate the real attention and liveliness (zing) it adds to the sound sig. Mine are unfortunately noisy and left one likes to crackle every 30 seconds or so. Will see if the situation improves after a dozen hours. I've already ordered EF86s+adaptors to alleviate this situation though, which should be better anyways according to the rest of this thread. Tried TS6sj7gt with them first; the tone was arguably even more beautiful, but I lost the sizzle and lively tone I have already mentally attached to this combo, so I swapped in RCA 5693s in the meantime. I'll update this post once i get the EF86. not as pretty and symmetrical as the metal jackets don't glow. GEC 6AS7G + RCA 5693 RED HOT Sound signature was, largely, identical to pairing with EF800 (main contribution to sq i've found is still in the power tube), but with less brightness/dare i say glare, and a more rounded tone across the spectrum. I think I actually prefer this combination's tone, but once again I miss the really active liveliness that is necessary for music that is presenting so much microdetail; without EF80's, the synergy just wasn't hitting the spot perfectly. I would gamble that the EF86 will provide the perfect compromise here. I will stick with this combo until i get the EF86s for the every so slightly more laid back presentation/tone, smoother mids, and more pragmatically lower gain so I have more room to turn the volume knobs. Volume matching is a task of its own but I did feel this combination compelled me to listen at slightly higher volumes than the EF80 pairing as it was less fatiguing/bright. I will alternate these with TS 7236+RCA5693 tomorrow to see which is the best for classical music. Can't imagine 7236 beating all aspects of the GEC! it is likely to remain my go to, at least for HD800.