Incompatibility between Dac3 and McCormack amp --- please help

[Voltron]

I sold my McCormack DNA-500 to a guy with an agreement that he could audition it and decide whether to go through with it. He uses his Bel Canto Dac3 as source and preamp. He goes directly into the amp, and I have asked whether he uses balanced XLR cables or s/e RCA cables but I have not heard back yet.

The amp sounds great with his Wilson Benesch speakers, but the problem is a buzz/hiss that is present and presumably most noticeable in quiet passages or when there is no music playing. He has contacted SMc Audio, Steve McCormack's shop, and has done what they have suggested (cheater plug, switch outlets, try a line conditioner and direct into outlet, etc) to no avail.

I am not sure if it is some kind of ground loop or impedance mis-match or what. If he is using RCAs, could XLRs possibly solve any issues? I have some Jensen Iso-Max transformers like these:

I could see if one of those worked for him as well as they worked for me when I had a similar thing going on. Any smart and knowledgeable Head-Casers have any suggestions for how to explain or resolve this mess? Thanks in advance.

[tkam]

Does he have cable tv that connects to anything that's in the same chain as his audio rig? If so tell him to disconnect the cable and see what happens.

Also if he has a PS3 tell him to use a cheater plug on that, it's notorious for dumping a lot of noise back on the line.

[n_maher]

Has he contacted Bel Canto? Ever used it as a preamp before?

[Voltron]

Does he have cable tv that connects to anything that's in the same chain as his audio rig? If so tell him to disconnect the cable and see what happens.

Also if he has a PS3 tell him to use a cheater plug on that, it's notorious for dumping a lot of noise back on the line.

Thanks, I will check.

Has he contacted Bel Canto? Ever used it as a preamp before?

No. Yes, with no problem.

[Voltron]

Any other ideas? I really would rather keep the money instead of getting the amp back.

[n_maher]

I would say that until he talks to Bel Canto he's only addressing half of the potential problem by simply blaming the McCormack.

[Aimless1]

I would say that until he talks to Bel Canto he's only addressing half of the potential problem by simply blaming the McCormack.

Have to agree. I really like the DAC3 but it can be quirky depending on the application. He should email John Stronczer directly [email protected] at Bel Canto, describe his problems, tell him what he has tried and ask for input. I've found John to be knowledgeable and potentially helpful. If he chooses to call he should speak to Matt Cramer directly (no voice mail or emails to Matt..he just does not respond).

[Voltron]

I would say that until he talks to Bel Canto he's only addressing half of the potential problem by simply blaming the McCormack.

In his defense, fwiw, he doesn't blame the McCormack or think it has a problem. He is just not sure what the problem is and why his other amp -- something tubey -- doesn't have the same problem. But see below, because I think he should at least check with Bel Canto if he wants to make an attempt to make it work.

Have to agree. I really like the DAC3 but it can be quirky depending on the application. He should email John Stronczer directly [email protected] at Bel Canto, describe his problems, tell him what he has tried and ask for input. I've found John to be knowledgeable and potentially helpful. If he chooses to call he should speak to Matt Cramer directly (no voice mail or emails to Matt..he just does not respond).

Thanks, I will pass this along.

[Dreadhead]

What is he using as a source? I've had ground noise issues with my DAC3 until I isolated it by using Toslink. At least from my computer the USB attachment had noise too.

What he should do first is just hook up the DAC3 and mcormick and speakers nothing else (ie no source to dac) and see if there is any buzzing. If so disconnect the dac and see, etc. It takes a while but you can usually find the cause.

The DAC3 should be dead quiet, or at least mine is after I got rid of the ground noise problems (without cheater plugs). It should not have any impedance issues either.

In my case it was my Linn Classik introducing ground noise (it was connected with RCA, while the GS-X was on XLR). Let's hope it's not your DNA that's doing this.

[aardvark baguette]

I've never had any noise whatsoever with USB or toslink. Those are the only inputs I've tried.

[Pars]

What is he using as a source? I've had ground noise issues with my DAC3 until I isolated it by using Toslink. At least from my computer the USB attachment had noise too.

What he should do first is just hook up the DAC3 and mcormick and speakers nothing else (ie no source to dac) and see if there is any buzzing. If so disconnect the dac and see, etc. It takes a while but you can usually find the cause.

The DAC3 should be dead quiet, or at least mine is after I got rid of the ground noise problems (without cheater plugs). It should not have any impedance issues either.

In my case it was my Linn Classik introducing ground noise (it was connected with RCA, while the GS-X was on XLR). Let's hope it's not your DNA that's doing this.

That is very good advice. Make sure the amp etc. is turned off before moving/connecting/disconnecting ICs and other pieces of gear.

[Voltron]

That's a great suggestion, Chris. Thanks. I will pass along.