My experience with Valve Equipment is that all devices can have their produced sonic changed when mounted on a Isolation Platform.
The Material for the Platform and Footer chosen will also create the perception that the sonic is reinforced in attraction of detraction. In general on a standard mounting platform there is added attraction to be found if trialing a few different mounting configurations.
As for the owner of the R8 referenced, the following is their words following the Group Demo' referred to:
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I mentioned that I'd ordered a set of China HiFi's recommended Psvane CV181-T MkII valves, to replace the 6SN7s in the Willsenton R8. Earlier experimentation with new 'Tung Sol' valves was a grave disappointment, but these Psvane tubes are different.
When you heard the amp at John's, with stock NOS Russian tubes, it sounded good, and probably better than its modest price might have suggested. Here, I could not quite decide between 'Triode' and 'Ultralinear' operation - the former sounded a bit weak, and the latter a bit too 'boosted' in the manner of a loudness control. I was aware that neither were optimal and the SuperNait3 was better all round.
Anyway, with the new Psvane tubes fitted, there is immediately more colour, air, textures etc - all the audiophile gushing stuff that says 'a really nice, musical sound'. Now, triode mode has a beautiful warm but detailed sound character with real grace and air; and there is now no need to go for ultralinear at all for extra tonal colour. The Willsenton amp is quite literally transformed into something that is not just 'rather good' but actually 'stunning'. I am pleased.
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Interesting to see the difference given as a description about the impression made during the Demo', as in all Audio situations each individual are with their own sensitivities to produced sound and have their own unique preferences for the sonic to be lived with.
There are other Upgrades to be found through a typical Web search, but the following link is showing a circuit Mod' that is one worthwhile learning about.