WA6 but standard wa6 not wa6se version (this sounded not so nice to my ears and cost 2x price of wa6) was the best sounding tube amp I have heard so far and I heard a lot of cheap/expensive stuff to drive different headphones (hybrid, pure SS class A/AB, OTL tube amps and OT - wa6 is OT what in my opinion gives extra drive and punchy sound comparing to wa3 for instance which is pure OTL design). WA6 with real mesh rectifier tube and some old school high impedance sennheiser headphones was like something hard to describe - velvet smooth but with amazing dynamics and bass extensions, best female vocals reproduction ever, great depth and weighty sound, extremely engaging and emotionally connected. I could lsisten all night long with hd600 and I wanted more in the morning. Now thinking about getting back to this way of listening music, even though in measurement test it would not be nice, but listening to the music is something different than watching measurement results. Too many times after epic measurements results it has nothing in common with "being there" sensation like in small chamber on the concert listening unplugged/unprocessed acoustic stuff etc. Too many times after measuring great it was lifeless, boring, analitycal and cold, I am too old to torture myself with this kind of "audiophile" stuff :> I want to enjoy the music, have a lot of satisfaction from auditions and feel emotionally connected to the performance on the stage.
Wooaudio stuff looks nice and is built like a tank but when you live abroad it gets even more expensive. I had in the past wa3/wa2/wa6 and wa6se and they cost little fortune when added shipping cost + customs and some extra fees, like 30% more from the total including shipping. WA6 was worth it, even with stock rectifier tube at the beginning to start with. Regarding WA6 I was talking about the old version with PDPS and 6DE7 driver/power tubes. These days it is 13de7 or something like that, they changed it so I can't be sure how it sounds now. There is also possibility to put 6SN7 when using some extra sockets - this is great because there is no better driver tube than 6SN7 - most euphonic tube ever made, period.