Ground Loop(?) leads to blow speaker


Aloha 'goners!
          I'm going to do my best to get the details down here as I am a bit stumped on this one.

I have a Wadia 121 DAC that was recently repaired.  The issue was the RCA/XLR outputs produced mostly noise and little music.  The headphone side was fine.

As the unit wasn't functioning properly I hadn't had the chance to hook it up and use it.  When I got it back and hooked it up there was a nasty ground loop(?) that led to a blown speaker (Thiel 1.6).  The buzz produced was the angry bee buzz followed by a loud electrical sounding crack and the woofer was gone.  The amp (Creek Classic A53) went into protect mode and I shut it off.  I then disconnected the Wadia and hooked up a Mytek Brooklyn+ and there was no buzz.  Same cables same outlets same everything except the DAC.  I tested the amp and it seems to be ok through another pair of speakers.

At this point I wasn't sure what was going on.  I tested 3 different amps with the Wadia and 2 of the 3 buzzed.  With the Mytek none of them buzzed.  Of the 2 amps that buzzed one of them had a 2 pin connection and the other a 3 pin.  The only amp that didn't buzz was a 2 pin Adcom 535 MkII.  The other amps were a 3 pin Creek and a 2 pin Carver.

Here is the full chain:

Primare CD31 --> Madrigal AES Cable --> Wadia/Mytek DAC/preamp --> Chord Cobra Vee RCA --> Creek/Adcom/Carver amps --> Tara Labs spkr cable --> Thiel 1.6/B&W CDM1SE speakers

I used the same wall outlets for the DACs and amps.  The same interconnects were used between components as well as from the amps to speakers.

I tested the wall outlets with a cabling tester and it said they were wired correctly.

Could there be something else that I'm missing that would be causing this?  The only amp I am comfortable with using to test is the Carver as it has a variable level on the front panel.

Any help or thoughts on this would be greatly appreciated.

solobone22
I'm not an expert of any kind, but what leaps out at me is the Wadia has a bad problem that is passing a very destructive signal down the chain. I think the volume must have been turned up a great deal as it was loud enough to blow a speaker (I'm surprised it was a woofer and not a tweeter).

I'm relatively sure what you're hearing is not a ground loop, but a sound I've heard unhappy digital equipment make when something is very wrong in their circuitry. I would throw away the Wadia, or at the very least, have it repaired properly. Sometimes, though, that can happen when something is not connected properly. So, check everything you can. Good luck,
Dan
Post removed 
It’s not clear to me what you mean when you refer to a "2 pin connection" and a "3 pin connection." Initially I thought you might have meant RCA vs. XLR, but several rear panel photos I found as well as the manual for the Creek amp (which you described as "3 pin") show it to only have RCA inputs. And the cable you indicated was being used between the DAC and the amps is an RCA cable. Can you clarify that?

Also, by any chance were you using XLR-to-RCA adapters between the DAC and any of the amps?

In any event, I agree with Dan that it does not sound like the problem was caused by a ground loop.

Good luck. Regards,

-- Al