Amplifier Power tubes - important to sound?

Their contribution was undoubtedly significant. The Gold Lions are a good sounding, generally reliable and long lived tube at a very accessible price point. I ran eight of them for the better part of a decade in my own kit.

The cost of tubes is another reason for going solid state. 

@darkblacksmoke

The VAC amps are amazing. I also have an older statement 450S (no iQ) for my smaller 2nd system. Of all a system’s components - the big VAC power amps were by far my most fruitful "splurge". For every other component slot, I’ve found cheaper items that yield similar or at least "close" results to my splurge-level items (of course a system’s components must synergize) - this includes the VAC preamp and phono. But I don’t know how to replace the big VAC amps - they’re wonderful. I particularly love them with Tung-Sol KT120.

As for the stock tubes you found - Kevin is not trying to be a broker of NOS tubes. His magic is in the voicing of components. I’ve done the KT120 swap and also prefer some of my old 6SN7 in V1, but for the most part these units sound awesome stock. I’m familiar with his choice of EH 6922 Gold and Shuguang 12AX7B (which are long OOP - he has a large stock). I think these sound very good, despite not being chic or expensive. I’ve got a large collection of NOS, and sometimes still choose Kevin’s 12AX7B for phono slots. Not familiar with the Gold Dragon 6922 (Shuguang?) - I thought it’s been a long time since VAC shipped any Gold Dragons. Of my vintage/NOS 6922, those tubes have been a huge pain in the ass for going noisy and various other gremlins - even sourced from reputable tube dealers. Just had a Brent Jesse Mazda 7308 go noisy on me, and before that an Amperex 7308 had its glass tube crumble out of the blue. I’m about to give the EH 6922 another go. I don’t blame Kevin for no longer supplying NOS. He used to favor Amperex 8416 when they were cheap and easy to find, btw.

Edit: I didn't know the Master has a "II" revision now, neat. Do you happen to know what that entails?

@darkblacksmoke

How would one go about finding where to purchase tubes from you? I think ethics are super important for sales and agree with yours.

Yes, power tubes are important, and not just for "tone."  I recently tested a variety of output tubes in my Williamson amplifiers.  Just to give a few examples, the Gold Lion KT66 produced the most power before passing 1% THD, 22 watts.  The Chinese TAD KT66 produced only 19 wpc at 1% THD.  Vintage 807s also produced only 19 watts before clipping, but at only .19% THD!  Dave Gillespie over at Audiokarma is an expert on ARC amps and he says that the Gold Lion KT88 is about as close to the GE 6550 as you can get, in terms of power output and distortion.  I've found the same with a number of small signal tubes, including 6SN7s and 12AX7s  In general, the NOS tubes perform better than most new manufacture tubes.