I have the WA5LE, and I found the sound decent with the stock tubes, but not overly impressive. Upgrading the tubes made a big difference. I did a ton of research, so here's how I went and why:
Rectifier: EML 5U4G Mesh
This was the easiest choice. I would really have gone for a vintage set of rectifiers, but I was very concerned about matching them. I do wonder how the amp would perform with a pair of GZ34s or a pair of 596s, but that's a big cost investment that may or may not pay off. Nearly every high-end review of the WA5 was based on the EML mesh, so I felt safe in that decision.
Driver: PSVane 181 TII
This is my weakest area for assessment. Having owned a WA6 before, I was hard pressed to find drivers I really enjoyed. The options aren't all that many here-- It came down to the Sophia, which I couldn't find many reviews about-- or the PSVane. The black treasures aren't made any longer, and the distributor said she tested the TIIs (Treasure series 2) and found them exceeding the Black Treasures in nearly every way. The TIIs are not as attractive as the Black Treasure, they are silver coated on the inside with an orange base. But they sound clean, and that's my priority when choosing a power tube. I don't want the power tube to overdrive or add too much to the sound characteristic, I prefer them to be relatively transparent with a lot of pure power for my massive HD800 bass drivers. The PSVane seems to do that.
Output: EML 300B mesh
There is more conflicting information on the 300B choices out there than anything else. Part of the problem is that the most recent thorough 300B shootout was done in 2002! Many of today's best 300B tubes on the market weren't available back then, and some in the shootout are no longer made. It comes down to two camps-- original Western Electric sound-- warm, not too much bass, but very very clean--- or the modern sound-- new designs which extend the bass deep, but in the process lose some of the WE magic. Tubes in the WE camp include the Western Electric itself (out of my price range at $2000 and up) the PSVane replicas, KR Audio, JJ Electronic, EML 300B Mesh (this one's actually more in the middle) and a few others-- In the modern camp-- Sophia Royal Princess, Sophia Carbon Princess, EML 300B XLS (EML's foray into carbon), Takatsuki 300B.
Of them all-- the Western is the sure-fire bet. It's tested, will last a long time, but will cost you the price of your amp to get a pair, if you can find them at all. They are going to production again, SUPPOSEDLY, in 2014. God knows if its true. The next best by many accounts is the Takatsuki, but find a distributor-- you have to go through Japan to get them and they cost $1600-$1800. No thanks. The EML 300B XLS and the Sophia Royal Princess are genuine contenders, they are supposed to produce a deeper bass than the WE 300B. But they lose a little musicality in doing so, if you believe the reviews. AVVT was another highly rated-- but they're out of business.
I chose the EML 300B mesh because I knew it would blow out the soundstage on my HD800, without sacrificing detail. Mesh plates (true mesh plates-- not Sophia mesh plates, which are stamped) are well known to produce a massive soundstage, and from my experience with these, that is most certainly true. This is a hybrid design-- it's based on the Western Electric 300B, but it is not a replica-- it's EML's own design. Also one respected reviewer whom I often agree with puts the EML 300B mesh above all other 300Bs except the Western Electric. They are amazing to my ear, but I do wonder if the Royal Princess or the EML 300B XLS would dig the bass in deeper. I'm happy with the EML 300B Mesh, at any rate. The EML 300B mesh is gorgeous to look at, but under power-- almost no glow!
One other word-- be very careful when pairing tubes with your WA5, the space is very very very tight between the output and driver sockets. Not all large bottles will fit together. My EML 300B mesh and PSVane 181's have an index card's thickness between them. They fit, but barely.
