Thanks, that's a big help in diagnosing this thing. This morning I removed the ground wire at the frame and cleaned very good down to bare metal and reattached the ground wire with no change in the whine. I also read that the ground for the amp should be separate from the ground for the capacitor but my ground wire leaves the frame then goes to a junction block and continues over to the capacitor so I'm about to separate those grounds to eliminate that as being an issue as well.
I've been interested in your build (well also sorry on the SO front). From what I used to do with this stuff 40 years back I especially noted discussion above surrounding ground loop. Beware my intel on this is mostly sourced outta my ass, but I had a big prob with whine that turned out to be components grounded separately - PLUS the blessing of an added periodic anoying 'pop' I answered the ground loop whine issue by joining all the grounds - so the part I highlighted jumped out at me.
For reference, the pop was from huge impedance mismatch between components purchased together from a supposed 'expert' stereo seller. Took 3 months tracking that down, and dealer tried 200 ways to get out of correcting his FU by providing me compatible replacements. And he lost. hahaha I learned something here that I'll remember when I go after putting in a Nexus 7 = avoid RCA wherever possible - thanks.
\'96SS SOB: SSRI, Herter Tune, Tri-Y II, , 3000 Edge, F/HO bars, METCO extendeds with CV MMC, Bilsteins, currently Vredestein Ultrac Sessanta (315/35 rear). Finally, wait for it... LT-4 knock module!
\'96FWB BUW-Butt Ugly White: PCMPerformance tune, HDFA w/ swissed filter, 1/2 SLP s.s. catback with H- and Flow Super 50s, oem opti rebuilt 3 times, SS Bars, METCO LCA, Airlift 1000, Monroe SS, PowerTrax No-Slip, CTS wheels with +1 rubber. Finally, yes again... LT-4 knock module!