Quicksilver audio silver 88 mono amps

@ gochurchgo: I will receive a pair of new Quicksilver 60 Watt monoblocks next week.  I intend to pair it with a Thor TA-1000 preamp with significant upgrades including about a dozen Vcaps.  The other preamp I have is nearly as good, but it's homemade, unfused and based on subminiature tubes so I don't know how helpful that is.  Come to think of it, the Thor is completely obscure, too - but interesting!  :o)

After reading for a couple of hours, I have ordered a matched quad of Psvane Black Treasure KT88-T Mark II to try as an initial upgrade to the stock Chinese tubes.  Other contenders may include the Tube Store Preferred Series ($280 per quad) or Sophia Electric KT88-ST (blue coke bottle, BUT starting at $500 per quad!).  JJ KT88 are also available for about $175/quad but I'm not sure they are at the same level; Merlin VSM speakers will reveal as much detail as they can get.  The VERY low end is handled by a JL Audio Fathom sub.

Any suggestions on the best KT88 to run in a straightforward pentode amp running some very neutral and musical sounding Merlin VSM floorstanding monitors?  Very slight tendency to brightness, with the wrong things upstream, but mostly to honesty (no gripes after 13 years with the same speakers!).

@decooney - Yeah, that heavily modified Thor TA-1000 is a special preamp, with a sound I would describe as detailed and authoritative, and neither bright nor dark. Its separate power supply probably weighs more than most components I’ve owned, but I could care less about the form factor.

These are NEW QS 60s received from the factory TODAY with all stock tubes, all brand new. Psvanes have yet to arrive.

One odd thing is that while both the website and owner’s manual reference an LED for setting the bias, there most assuredly is no such thing on my amps! Instead there are ports for voltmeter probes (regular ones, not the 1/4" jacks on the old QS amps).

Since the manual provides no actual numbers, I don’t know what bias current to target. They both ramped up to 70 mA after I installed the factory tubes so I figure that must be close - I’ll call the factory tomorrow. Does anyone here know the actual factory recommendation for THIS current-gen. Quicksilver "60 Watt" mono amp (there have been various QS KT88 amps over the years)? I don’t care about the LED indicator; as an Electrical Engineer and irrepressible tinkerer I would rather use a meter anyway.

This is in regard to the Quicksilver 60 monos I got new on 11/11/2020: I was getting a *little* brightness or glare which I attributed to the Esotar tweeters in my Merlin VSM speakers.  They are still the best amps I've found for the Merlins I've had since 2007 and I've tried a BUNCH of them, solid state and mostly tube.

I've been upgrading fuses in my other components and eventually decided to take a look inside the Quicksilvers.  Much to my surprise I found Synergistic Research Red!  I immediately ordered a pair of Purple to try - that's what I just stuck in the Thor TA-1000 preamp and ordered for my PS Audio DirectStream DAC.

In the interim I found a pair of HiFi Tuning Gold fuses I bought cheap on closeout a couple of years ago.  Stuck those in the QS 60 mono's and WOW!  So much more body in the mid-bass and mids, FAR better bass extension and the rest of the music is still there.  I have to believe that the Reds were a step up from a $1 glass fuse but the HiFi Tuning absolutely blows the Synergistic Research "Quantum" Red fuse away.  I'll keep them as spares.

Now I'm KEENLY interested to see how SR Purple fuses compare to the obsolete HiFi Tuning gold in my beloved QS monos.