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

I disconnected my preamp yesterday completely from my system in order to install some constrained layer damping tape.  The DAC was on and receiving music, but the signal chain between the power amp and the dac was completely broken due to the preamp being removed.  BUT:  I could hear very low volume, but very clear, music playing thru the speakers!  And no, I was not intoxicated.  How is this possible?  Cool stuff.  Thanks.
Granted it is not easy to tell the April Fool’s from the normal everyday variety. I have to work very hard at it. One even has a whole entire website, a veritable shrine, the Las Vegas of Fool’s. But I can’t complain. At least not today. The other 364 days though....
This reminded me of something that really truly happens with my system. I don’t think it matters but I have a Denon AVR 4806 ~10 yrs old & we have outside speakers.  Although no one is allowed to touch it, once a yr sound starts coming out of the outside volume switch. It’s very faint & you can feel the switch plate vibrating a little.  A call to my stereo store & after some... push that, turn that switch all the way to the right & then flip that toggle down twice & once up... its gone. So, can some kind circuit  or set of wires, in the volume switch, vibrate when you “cross the streams” & cause that sound?  It’s usually the radio or what I’m trying to play outside from my iTv iTunes.
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:


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