Hi:
I've identified the sources. Problem is noise on powered speakers when no audio is playing. Strange buzzing when no audio playing (turning speaker off is not simple). When I moved the output device next to speaker problem disappeared, Putting it back in place puts it in proximity to 2 12VDC lines to LED fixtures. When both lights are off, no noise. The analog audio is running through wall and although SPIDF output is available, no co-ax or optical cable is available plus conversion on speaker side.

From what I can tell, the noise us being transfered wire to wire due to proximity. If I use a shielded cable for the analogue output to the wall (seems like easiest direct shield) I can try that first, then if attenuated but still present ground the shield on one side. Total length is 24". Another alternative would be to deliver the 12 vdc to both lights using shielded cables. I've experimented with both 5vdc and 12vdc circuits that were running parallel to Cat 6 and found that I could detect no EFI coming from either 5 or 12 VDC sources (using a crude AM receiver). Both sources generated plenty of noise around the sources (wall bricks). I used TV coax on hand, but now have some 18 ga 2-conductor cable with coper wire shielding. With the coax no drain to ground was needed, nor did it make any difference. These cables are longer but both 4' each and easy to access.

Initially, I was thinking I had a power supply to speaker problem, but speakers have internal batteries and connecting power does not make or affect noise, it's all coming down the analog audio lines.

 

CERTAINLY the DC power lines to LED lights will be noisy. That is because LED lighting is lower voltage and greater current, all with either switcher supplies, or with switcher supplies PLUS PWM control. Those are basic to LED lighting.

There is good news, though, which is that there are several ways well known to reduce noise transfer, since it is not a new problem.
Twisted pair wires is one scheme, and good shielding is a second scheme that also works. In addition, balanced circuits that tend to cancel induced noise are useful. Shielded twisted pair audio cables are a common solution as well. There are whole textbooks on the topic of shielding and noise transfer protection.
The strongest protection is the BALANCED shielded twisted pair connection, with the shield tied to a suitable common at one end only.

 

I think shielding the cable is the easiest solution.

 

I think shielding the cable is the easiest solution.

If you use a single shielded conductor, the shield will pick up the radiated noise. A twisted pair is much more effective. Shielded twisted pair is even better.