Generally, you shouldn't hear any whine or "wrrrrrrrrrrrr" anytime. If I had to guess, I would say it sounds like you have a bad ground somewhere, or a different resistance between your grounds. A dead-on sign of this is the "alternator whine" that your hearing, especially if it's different at different engine speeds or if you still hear it when muting your audio.
Dunno if your interested, but some suggestions on things to try to get rid of it:
- Undo all grounds (or rather, all grounds related to your a/v) and clean the metal thoroughly
- STRIP ALL paint away from the grounding point, no matter what.
- Reduce the amount of different "metals" that your grounds go to. For example, try to have all grounds attach directly to the frame. As compared to, say, one ground directly on the frame and another on the floor sheetmetal. In this example, although the sheetmetal contacts the frame, there will be different resistance in the electrical part between the two grounds and will cause hum.
- Upgrade the "big 3" wires, especially if the amount of amps you're pulling is close to the limit of the alternator --- alternator positive to battery positive, battery negative to chassis, and engine ground to chassis.
I had this in my Jeep Wrangler, and it took a little bit to get rid of. Turned out the third one was my culprit.