Weird

I have the grandfather speakers to your GoldenEar's

the Definitive Technology Mythos ST's that have powered subwoofers also

When l walk by to get a wobbly pop l aways lightly touch the drivers

and woofers of both speakers to make sure everthing is working 

Mine also has seperate volume controls and assuming yours also has the same and more with DSP Double check that everything is set in balance 

Richard, remember when we tried the Ayre AX-7 and it kept going into protection mode? This makes me think your subs may be out of phase.

But, if plugging directly seems to have corrected this, then, please ignore.

B

Curiousjim,

The power cord fell off the subwoofer.
I mis-spoke calling it a lead.

Just a thought…

With two subs active now you’re probably exciting the room bass nodes and the added bass just overwhelms the rest of the frequency range. 
Dial the bass output down on both speakers until you get tight bass that doesn’t overpower the mids and highs.
 

I’ve experienced this with the Martin Logan Montis speakers that also feature powered woofers. 

you can use low frequency test tones to dial in your bass output. 

Try them with both subs on pulled out a bit more in your room.