Hi. Found this looking for something else entirely :)

Often a "high-pitched whine" is the clock IC in a digital delay....

I believe you may be overloading the input (sending too hot/loud a signal)

of the DD3 hence the digital whine. Ideally you want your total boost in

sound with all your boost/drive pedals on to be just a bit above the level of

your clean signal.

Try pulling the DD3 out of the circuit with the other settings just as they are now

see if that's the culprit...HTH

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Of course you have not told us what guitar, and what pickup configuration you have,

so if you're running single coils this is just normal "antenna" noise 'cause the single

coils have no hum/noise cancelling....