OK, I'm stumped (but that's not hard to do).
I have a Luxman R-117 and two pairs of speakers, some VR3-modded Polk SDA 2s and Atlantic Technology AT-1s.
The Lux and AT-1s play great together.
When I unplug the speaker wires from the AT-1s and plug them into the SDAs, the Lux's protection circuit kicks in intermittently (i.e., the red light on the volume knob goes dark). I just retrieved the Polks from Speakerlab, and the tech there said he played them for half a day with no problems (although using another of my receivers, a Denon).
Before I took the SDAs to Speakerlab, they were tripping the protection on the Lux and the Denon within a few seconds of getting signal. Speakerlab found a bad tweeter in the Polks, which they replaced.
When I got the speakers home, they exhibited the same problem as previously, although sometimes they will play for minutes at time (rather than seconds) with no problem.
A little history: I modded the Polks back in December with the help of a great local Polkie. The speakers worked great for about four months. Then I got the itch for better amplification, the ordered a Teac integrated online. I was DUMB! I didn't check to see if the Teac was common ground (which it isn't!). That's when the problem started.
As I said, Speakerlab found nothing wrong other then the bad tweeter, which we replaced. And the problem only occurs when the SDA cable is attached.
I'm stumped. I hope some of you big-brained Polkies may have some hints or suggestions. Thanks.