The issue is I need to power the project from a single supply. I'm also using a 5V 10A supply. This should be more than sufficient to handle the power requirements but when I play anything I see the low voltage indicator crop up on the pi. And the high pitched issue continues to exist.
Failed to mention that I also clamped ferrite cores to the microUSB power cables (both sides of each cable). Reduced the noise, but still there.
Tried briefly (just for confirming) powering the whole setup using a 13000mAh USB Power Bank for "pure" DC supply. Noise gone (or have gone unnoticeable to me). However this method may be a bit impractical for you.