Amazing Amp but before becoming too exited, here some flaws with it. (new revision with 17AX4GT Rectifiers and updated driver tubes)
- With very many NOS tubes, exept the crappy new stock driver tubes, you will hear Hum noise with dynamic HP´s 300 ohms+ or in other words, with all Sennheisers and 600 ohm beyers, even on low gain and volume 0.
- With stock tubes the HA-6A sounds not worlds better than the HA-3A, maybe very slightly different but this is easy negligible. Using KT88´s is adding some more bass and transparency but that's a matter of taste. Most people buying tube amps not for SS sound but for tuby sound.
- HA6 sucks continuous 140watts, HA3 70 watts.
- Both amps are not pairing very well with Sennheiser´s, especially the HD 800S sounds like boring crap on both (stock tubes EL34)- even a LD MKII pairs better with a 800S.
Otherwise the HA-6A is a very good sounding amp, especially for planars.
As long as you don't use headphones that are very difficult to drive, I would easy recommend the HA3, you won't lose anything if you bought the cayin for his tubey style rounded sound and if you don´t need the slightly more SS sound from the KT88´s which are btw. no longer included to the amp.
Before you call me a heretic, that's just my experience.
cheers