I have the following Sonic Frontiers equipment:
- SFCD 1
- Line 3
- Line 1
- Power 2
- Phone 1
All of them have been upgraded by Chris at Parts Connexion to their full extent or almost full extent. Each one is dead quiet.
Some of this equipment I bought new and some I had bought used over 20 years after their initial release. I only replaced 2 of the units so far:
- the fully upgraded Line 3 and upgraded to the current Audio Research 6SE (which is slightly more transparent, just as fast but misses out a bit on the musicality of the SF Line 3)
--- while the AR 6SE does sound absolutely wonderful and does exact more transparency I do miss the musicality of the line 3, was the AR 6SE worth the price? Only because I picked up a barely but gently used one for a fantastic price. Otherwise no, I don't think it was worth the cost to change preamps. Yes, the Line 3 is just that good. - the power 2 stereo amp to 2 Bryston 7B3 (the Bryston's don't give off the tremendous heat of the large tubes of the Power 2, the Bryston's are a bit quicker but loose out in their holographic nature, both have tremendous mid's and bass, both are very quick)
--- the power 2 does not hum, buzz or sound bad in any way shape or form like others have said. It is a beast that throws an absolutely killer 3D soundstage, with conviction. The only reason I switched it out was because I didn't want to deal with the tubes and their heat any longer. I auditioned the regular suspects to replace it -- Boulder (way over priced for what it is and in a blind test picked the PS Audio BHK amps and the Bryston's 3 out of 3 times as my preferred sound), Parasound (okay), PS Audio BHK, etc., but found the Bryton's to be almost indistinguishable from their competition, better built and running cooler. (this is specifically the cubed series though I would not have bought the older equipment as I don't think it was as good sounding... the cubed series is a leap beyond their older generational equipment)
The SFCD 1 and the Phone 1 are still operational in my main system and sound amazing... the Line 1 is in a secondary system and sounds as musical as ever.
Hope this helps.