High Pitched Frequency From Speakers, tried everything - - - Driving me crazy, help!

Hi All,

I've been having issues with a high pitch frequency coming from one channel of my speakers intermittently throughout listening sessions. It's a very high whine, think like the sound of a fluorescent light but higher in volume. It comes and goes on its own, does not change in volume when I change volume. It seems to only come on when a source is playing through it. If I mute my preamp it goes away. 

Sometimes I'll have a great hour long listening session and it won't come on but sometimes on the first record it does, same if I'm playing through my dac.

It started in the left channel but now seems to have moved to the right channel only. I thought it might have been tube noise/old tubes in my preamp so I swapped left for right. It went away for a day and then started in the other channel, great just need new tubes. Bought new tubes,  but nope, still present in right channel, swapped left right channel tubes, stayed the same. The new gold lions sound so much sweeter than the JJ's, so I'm very pleased about that, but still extremely frustrated! 

Here's my setup -
VPI Prime Scout
Musical Surroundings Phonomena 
Rogue Rp1 Tube Preamp
Rogue St90 Power
Vandersteen Model 3a sigs
Cheapo Schiit Dac for movies
Panamax Power Conditioner

Here's what I've done (to no avail) to troubleshoot the issue - 
-powered preamp and amp on different circuits (note I usually have them in a power conditioner)
-plugged amp preamp directly into wall
-bypassed phono stage and used one in preamp
-swapped speaker cables
-swapped interconnects
-did channel testing swaps (did not move the noise from one channel to the other)
-replaced and swapped preamp tubes
-replaced and swapped power amp tubes
-swapped out tube power amp for solid state (also was a a nice surprise how much better it sounded)
-separated all power lines from interconnects and speaker cable
-cleaned all connections
-appears with either source playing

I recently downsized my audio gear so I do not have an extra preamp or set of speakers to swap out.

Any insight, advice, help would be greatly appreciated! I am truly going mad over this.

Thanks in advance,
Sammy