Well, i’m glad to hear that something fixed the no noise issue. But since you don’t know what solved it, it may not actually be fixed and it may stop working again. The high pitched noise may be related to the same issue. Make sure your solder joints are very solid, fully connected and nothing is bridged. There are lots of things you could be getting this high pitched noise from. One of them is the power supply. You can try to use a battery to see if that would help, or a linear power supply (not switch mode) like the Boss PS series…basically anything with a heavy transformer in it. Another thing that could be causing the high pitched noise is the PWM signal leaking into the audio signal. Since this noise is adjustable with some controls, this is probably what it is. Hopefully cleaning up your solder joints will help with this. Lowering the volume of both the high and low signal paths may also help with this.
Keep me posted about your solder joints.
-Brach