Amplifier Power tubes - important to sound?

I don’t believe you. The 807 uses a top anode cap and a seven pin socket. It is not swappable with octal power tubes. I had some in my tube collection.

I thought that was odd too. Maybe a weird typo?

I’ve used a Williamson amplifier (pair of Heathkit W5) with Gold Lion (Russia) KT66 and it was very "powerful" sounding with strong bass, good "slam", and plump full mids. The same amp, fitted with vintage GE 7581A (near KT66), sounded more airy, spacious and articulate with a gorgeous midrange - but leaner in bass.

Sadly, power tube rolling becomes quite painful in amps using more than a quad. Vintage/NOS is pretty much out of the question. BUT once you get so many push-pull pairs in parallel - that’s where the real magic and beauty of tube power lies for me. On just one push-pull pair per side, I will certainly prefer the tonality of EL34, 6L6GC / KT66 over KT88 - at least until I run out of power,

@carlsbad2 : The 807 is a seven pin top cap connector anode tube. It is not swappable with octal power tubes. So how can you compare it to the common octal power tubes as you claim?

@jasonbourne71 They make adapters.  Very common. 

@jasonbourne71 I’m sorry, what are you talking about? It’s very easy to substitute an 807 for a 6L6 or KT66 with an adapter socket you can buy on eBay. You just have to be careful to observe the lower dissipation rating and keep the plate and screen voltages at 400VDC or below. The 807 is pretty much a 6L6GB with slightly higher max ratings. My amps will accomodate KT66, 6L6GC, 5881 or 807. And the 807 uses a *five* pin socket. The 1625, the 12 volt version of the 807, uses a seven-pin socket.

All…please be very diligent and extremely careful recommending tubes for OP’s system. The tubes must be on a good enough level to not embarrass the amps that will be driving a $50,000 pair of speakers that OP is looking to purchase. Please continue your battle on tube choices, plate voltages, tops, compatibility , requirements and adapters. I’m sure all this information will be extremely helpful to @emergingsoul 

And just curious, @emergingsoul , with you being so impressed with Jay’s Audio Lab, are you contacting him for an advice. What did Jay say about your setup and future plans?