I must be lucky, not having microphony issues in my LP 3.1 and Universal setup (in Brooklyn Home). The same goes for my LP 27 and Triode SET amp (Upstate). I do plug in my amps and preamps into either an AVA Humbuster or Emotiva AC line conditioner. I think this may help a bit to clean up Con Ed's dirty power.
I do get a slight bit of 60 Hz hum, with an ear close to the speakers, 89 SPL GR Research DIY Studio Monitors and Jeff Bagby's (RIP) 95 SPL Fusion 8's. I had a JAN Ratheon 5U4 in the Universal Amp that was causing noticeable hum from my nearfield listening position. I replaced it with a NOS Dynaco labeled 5AR4, much-reduced hum. Also, I have had great results with a 5AW4 CBS Hytron (an underappreciated tube IMO). This is currently powering up Dynaco 6CA7's, really loving this combo; I'm using an RCA 6SL7 as the driver tube. Very lucky to have scored the Dynaco tubes out of a gifted ST-70. Tubes tested good and sound very good-now I see what all the fuss is with NOS Power tubes.
In the LP 3.1 not had any microphony with both Westinghouse/GE branded 6SN7's. Currently really enjoying the Westinghouse tubes buffered by Sylvania a 6BX7. The rectifier is RCA 5Y3.
I do not keep my amps on 24/7. I want my NOS tubes to last a long as possible!
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