I completed my Stereomour II a few days back. The first few days I was really impressed with the audio. The hum pots were dialed into 0.000V and all that could be heard out of my Kilispch RF-7II was a nearly undetectable hum with ear to speaker. Curiosity got to me so decided to do the DC filament upgrade sooner than expected and yes indeed, the hum went completely away, but I was wondering if what I was hearing was better or not. It certainly was different but it seemed the bass (and something else) was shaved off a tiny bit. Otherwise the sound was tight.
Enter the Shunt Regulator upgrade. I just completed it a couple hours ago and I can't quite believe the transformation. This is a major step up IMO. The sound stage is much larger, like someone in the band said "ok we're too close together, let's spread out some". The bass appears to have reappeared in spades, full and tight. Clarity and increased depth in all directions. Really crazy, I would have never thought the improvement would be this much. I'm usually skeptical of many claimed audio hardware improvements with upgrading, but this one is night and day IMO.
When I was doing the upgrade it was only then did I realize all the extra pins of the 12AT7 that were not wired. It seems now the 12AT7 is being fully utilized??? Is that what is contributing to the massive improvement? My Klipsch speakers have NEVER sounded this good. My 75 pound SS power amp is now being retired.
Anyway, this has been a really worthwhile journey building this amp. The instructions for all of it were flawless and the kits were not missing a single part. OUTSTANDING! One Mour upgrade to do, the MourQuiet.