Do clothes make the man?

How can one determine if swapping vacuum tubes results in better sound, without trying all sorts of alternatives?

For me at least, that’s the allure of tube rolling. I find it interesting to hear the variations. 
 

Beyond that, who seeks to buy Russian OR Chinese stuff? I prefer NOT to. This is not anything but a desire to not support them.

I hear you, but beyond Western Electric in the U.S. and JJ Tubes in Slovakia (if I remember correctly), what other major manufacturers are there outside of Russia and China? And even then, I would consider Western Electric boutique and far from a major manufacturer since the only tube they currently mass produce is the 300B. 

Or were you referring to NOS? But even then rectifiers that could be had for $12 pre-pandemic, are now running between $45 - $75 depending on condition and with no guarantees.

Personally, I can’t afford NOS power tubes whereas driver and rectifier tubes may be in reach given their general longevity. 

"You’d think Quicksilver would supply better-sounding tubes in their amps."

@noromance Those amps were bought used. Mike at Quicksilver does not use those tubes in his new amps!!

@yogiboy Noted, and relieved. 

@yogiboy +1

Mike

I’m glad you found tubes that sound good in your amps.

"unbranded Viva Tubes" ?

Viva is a seller, not a maker, and all these tubes they sell have the maker’s identification listed in the ads and printed on the tubes.

https://www.ebay.com/str/vivatubesnosvintagevacuumtubes

from Quicksilver's site:

"As with all Quicksilver amplifiers many different output tubes may be plugged in directly with no adjustments:  Matched pairs of EL34, KT90, KT88, KT77, KT66, 6550, or 6l6 output tubes".

what was in it?

I like EL-34s and KT88’s. I’ve used some of the others as temporary until I research and replace them with .... 

do you have a tester, IOW, perhaps the tubes that came with it were weak or bad?