I thought I better chime in.
Thanks Leftside for setting up the thread. Great idea.
I've had the WA22 for about 18 months now. I'm kinda polarizing (a few lovers and haters) however I've also done a lot of experimenting. So I will share a few discoveries. I've discovered a few gems and also a few frustrations (to be expected with tube amps).
My few gems.
I discovered the Brimar 5Z4GY early on and reported how great it was. From there it proved popular with Woo users. Langrex in the UK has at great prices and seems to have plenty of stock. Contact James.
SS rectification was very nice. Especially the Weber copper caps (WU4G). If I didn't have a state of the art SS amp (Violectric V281) I would run the WU4G in my amp permanently. WU4G provides a very clean detailed sound. More than most rectifier tubes. Very good bang for the $$'s.
This was discovered purely by accident. 6C8g tubes work fine as drivers. I had purchased 6F8G and was supplied 6C8G. It had been in my amp for two weeks when I noticed it was a different tube. I contacted Jack from Woo and he confirmed it was fine to use. So I stocked up on Tung-Sol roundplate and National Union 6C8G's. They are lot cheaper than the 6F8g. I now have 16 sets of TS and 8 sets of NU. NU doesn't play nicely (noise) with some power tubes. It does work nice with my favorite power tube (GE6AS7GA) so I stock a few.
TAK274B is a damn nice tube (it may be worth the $$'s). I stock a couple of these. I've recently got the 596. That competes with the TAK274B however you can't use any other tubes with wire grids like the 6C8G/6F8G mention above. They create a buzz sound.
6BL7 power tubes are real nice. Very holographic. Runs the amps very cool. You can use singles as a direct drop in or buy adapters to run two per socket.
DeOxit is great and it should be in every tube amp owners care kit.
My few frustrations.
Some power tubes don't play nice in the WA22. They produce a background noise when mixed with the wrong type of driver. Occasionally the rectifier can cause issue as well. Basically synergy. WA22 is unforgiving with a number of power tubes.
The power tubes I've discovered that can be of issue are:
Sylvania 6080 (can be a hit or miss (out of 4 tubes 3 were noisy)).
Mullard 6080 (can be a hit or miss (out of 6 tubes 2 were noisy)).
Like I said sometimes changing the rectifier or drivers can help. My experience is that RCA 6AS7 and Sventlana are a lost cause. If you get a noisy set nothing can keep them quiet. RCA6AS7 can be labeled up (I've owned all of these versions) Raytheon, Sylvania, Tung-Sol and GE. So be careful to look at construction. Out of 6 sets of RCA6AS7 none were quiet. I would not recommend RCA6AS7G for the WA22. These same tubes were dead quiet in the Woo WA2. So there is some circuit differences between the WA2 and WA22.
I've never totally drank the tube amp kool-aid. My WA22 (my first and only tube amp) has been fun and for a long while been my best sounding amp. However it is now beaten by my Violectric V281 SS amp. Probably my most polarizing point. This is not the place for any discussion. I just point it out as I may be biased. WA22 is staying as it does produce something different to the V281. Different is good.
I will leave you with a few images of tubes I have tried:
My system. Woo WA22, Violectric V281, Auralic Vega DAC (huge improvement) and I use AudiQuest NightHawks and the Audeze LCD-3C headphones. I don't use vinyl on HP's. I can't get past the crackling sound.
Brimar 5Z4GY used with twin 6BL7 power tubes. Like Leftside has mentioned I have used 6BL7 as well. Fantastic power tubes.
Weber copper cap WU4G. A really nice combo. Very clean sound. A lot of hum left my system after using SS rectification.
Probably my favorite combo. TAK 274B, Tung-Sol 6C8G and GE6AS7GA.
Right now this is what I'm using. 596 rectifier, RCA 6SN7 and GE6AS7GA. Purely experimental at this stage. However early listening is very positive. I'm surprised how well the RCA are doing in this combination. Usually RCA6SN7 is a little treble rolled. At the moment I'm hearing a little roll off but better than I've heard before. It could be a good on-going combo.
That's all for now. Peace.