Wow, NOS... initiallyAloha,
I have acquired NOS tubes and listened. More toobs are yet to come in. No mods on the unit, only toob rolling.
I have an abundance of 6080 and 6AS7G gathering. The better toobs are metal based 6080 for power, but the bakelite base 6AS7G appear to be more open. Surprisingly the 5998 has slightly more bass with lean mids, and some high extension. My favorite toobs are lesser known 6080s or 6AS7Gs.
Interesting are US 6AS7G tubes that are really compressed midgets in straight tubes rather than the ST form or longer tubular envelope. At first glance, I thought these were 6080 tubes owing to their tubular envelopes, but they are short.
The greatest influence on the sonics of the WA3 come from the 6922/6DJ8 or its variants. I used a set of Siemens E88CC, wow... what details and musicality! The next best was a cryo JJ 6922. More variants to listen to and have yet to come in. Realize that I must focus on the factory codes and contruction details to drill in on what I am looking for. The toobs are not really what they are marked as.
Will place a more comprehensive commentary when my toobs are finally in and I begin to do a formal listening.