Another vote for "naked" Vishay resistors. It is amazing how they transformed my Counterpoint NP100 power amp.
I first got a Counterpoint SA100 as my 2nd system. It was quite musical. But it ran too warm, and it sounded better the warmer it got, by adjusting the biases. Then I upgraded it to NP100 Basic. It ran much cooler and sounded a bit better.
Then I upgraded it to NP100 Basic Gold. It sounded real nice then. So I moved it to my main system and moved my KT88 monoblocks to the 2nd system. I thought it was good enough until a friend brought his NP100 Premium Gold to my house. The NP100 Premium Gold has "naked" Vishay resistors in the critical signal path. Within 30 seconds after switching to his NP100 Premium Gold, I knew that I had to upgrade my amp.
Instead of upgrading to the same level, I chose to upgrade my amp to the top level, NP100 Platinum, which uses "naked" Vishay everywhere. It was a very expensive upgrade. But the results are amazing!!
I think I am set with my power amp, after the "naked" Vishay upgrade. Now my NP100 Platinum drives my JMlab Alto Utopia with authority and yet is so refined like a SET amp.