A Ghost in the System? Music Thru Speakers with Preamp Disconnected

Well, you have either of two choices. It's coupled through the AC, or it's RFI/EMI coupled.


Try removing the interconnects altogether. They may be acting as antennas. Next, attempt to move the DAC closer and further away. You should get louder, or softer.


If neither has an effect, it's coupled through the AC power line. I suggest you split your devices up by either using multiple good strips like this Furman:

https://amzn.to/2YEBR5L


Or use a more advanced unit with multiple filter blocks. Furman, Shunyata and others.

By disconnected, do you mean you removed the interconnect cables?

If yes, then power issue. If not, you are getting crosstalk from the preamp, though it is usually thought of as a Left to Right thing, it's also possible to get it from one input pair to another.