This post brought a big smile on my face...
Back in 2002 I took Pete's design and started doing rounds and rounds of PSU design testing and tube/components permutations and started harrasing everyone around, including Pete (who kindly explained the design and suggested things to try)
The fact is my final setup is still over a woodboard, never cased it up as I thought it was overkill and wanted to test other amp designs, as everyone told me WCF were a very constrained design in terms of improvement.
In short the beefiest and more expensive section of the amp was the PSU, its design had the most impact on final sound. I end up with tube rectified (5C3S) to a double LCLC stage with plenty capacitance (900uF). Used a seperate transformer for 6.3VAC heating. B+ was around 210VDC.
I tried tons of input and output tubes, including paralleling sections, the final tube chosen for input was a 6H30P-DR, and the output a 5998.
With that coupled to my K401 (120Ohm, 89dB sensitivity) sound was incredibly organic, plentiful of controlled bass and overly lush while having very good distortion figures and characteristics. I'm not a classic music listener but know how real instruments sound like, and strings and piano sound was incredible. I did some sims aided by Alex Cavalli but ended up using pots and fiding sweet bias spots by ear.
For inputs I tried Ecc88, 6SN7 both short and tall bottle, 6N1P and 6H30P-DR. Sound with the 6H30P-DR was clearly the best, sounding like an octal tube in terms of distortion characteristics but like a noval in terms of "definition" when biased in its sweet spot. 6N1P was second best but more analytical.
For output I tried 3 different 6AS7 NOS tubes, a RCA 6080, svetlana NOS 6C13C, and TungSol 5998. Also 6H30P-DR. Tried paralleled sections, etc...
A single 5998 came out as a winner probably due to its lower Zo as advised by Pete, followed by the 6C13S.
The key there was to run it hot enough (original Waarde amp didn't sound quite right to me) and the kind of Rk resistors used.
Of course the output caps were key, I tried tons of kinds and combinations and in the end I found the Solens to be the most neutral, there are non electrolityc caps today much better than the Solens...
In the end I discovered I needed a better source also but that got put on hold until recently I buillt a USB based DDDAC and tube DIY "sparked" back on me . I may give it another shot!
Can't wait to see the final Menace design published!