Just hooked up -good sound- then problems started

[Dynakitbuilder]

Just got the system connected last Monday (2/24).  Good sound, everything worked. Next day the right channel on phones (only) transmitted a lot of static, but only intermittently, with no static on speakers; would totally go away, then return. The static returned each day and then stop, with return of good sound.  Today, I turned on the amp and no sound whatsoever.  No source input.  System: iMac, USB (audio quest pearl) to Schiit Modi 3.  RCA interconnect to amp.  Headphones: Sennheiser HD600.  Speakers KEF Q35 sensitivity 91db. Tubes glow as per usual. Rechecked all connections on surface.  Have not looked under the hood, so far!  What next?  Thanks in advance.

[Paul Birkeland]

Voltage checks.

[Dynakitbuilder]

Thanks - I will get on that.  Just checked computer sound output preferences and somehow sound was muted.  So, all sound is fine into the amp.  Just concerned with static in R channel. Will advise.