[Drue]

Dear Head-Fi,

I recently picked up a Cavalli Tube hybrid amp to complement my THX 789. I use a SMSL M300 MKII dac which I run XLR into the back of my 789 and I run SE into the CTH. If I try to use the CTH with the THX 789 turned off it sounds terrible. I'm talking complete distortion and crackling, but the second I turn the power back on the 789 everything goes back to normal. If I plug in my CTH into the dac without the 789 plugged in everything sounds perfect as well.

I wanted to ask for any ideas on what is going on since this is beyond my pay grade and I'd really like to keep them both plugged in so I can A/B, but I really don't want to keep my THX789 turned on just to listen to the CTH on its own. Thanks!

 

[Raketen]

Maybe some type of relay inside the thx that picks up when it turns on & isolates a part of the circuit that is causing your issue- for instance it's possible this DAC is just not meant for using multiple outputs- I am more familiar with portable stuff, oftentimes those gadgets with bal & SE output bridge their opamps for the SE output so using both outputs at the same time could result in some issue.

In terms of solutions: Have you tried just using the SE output to both amps? Alternately, if you don't mind a bit of a hack you could feed your outputs through a switcher.
For instance I believe a unit like this would give you the ability to switch between outputs so the one not in use is isolated (might be cheaper/smaller examples https://www.amazon.com/ONE-Little-Bear-Balanced-Converter/dp/B00OY0TBMA/

 

[Drue]

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[Drue]

Maybe some type of relay inside the thx that picks up when it turns on & isolates a part of the circuit that is causing your issue- for instance it's possible this DAC is just not meant for using multiple outputs- I am more familiar with portable stuff, oftentimes those gadgets with bal & SE output bridge their opamps for the SE output so using both outputs at the same time could result in some issue.

In terms of solutions: Have you tried just using the SE output to both amps? Alternately, if you don't mind a bit of a hack you could feed your outputs through a switcher.
For instance I believe a unit like this would give you the ability to switch between outputs so the one not in use is isolated (might be cheaper/smaller examples https://www.amazon.com/ONE-Little-Bear-Balanced-Converter/dp/B00OY0TBMA/

That is so disappointing if that would be the case. My entire plan to run both of these goes down the drain I just wish I knew for sure that changing dacs would fix the problem. In this case I don't know if it is. I'm going to have experiment with plugging different things in I guess I have a Modi 3 laying around somewhere.

 

[Raketen]

That is so disappointing if that would be the case. My entire plan to run both of these goes down the drain I just wish I knew for sure that changing dacs would fix the problem. In this case I don't know if it is. I'm going to have experiment with plugging different things in I guess I have a Modi 3 laying around somewhere.

Well just speculation on my part, could be completely wrong- try asking on the SMSL's thread maybe. Could also be some type of power/ground loop or interference issue.
I see the THX has a SE passthrough, at least as a temp solution, you could do single end everything, RCA into the THX single end, and then use the SE pass to the CTH.

 

[Drue]

Well just speculation on my part, could be completely wrong- try asking on the SMSL's thread maybe. Could also be some type of power/ground loop or interference issue.
I see the THX has a SE passthrough, at least as a temp solution, you could do single end everything, RCA into the THX single end, and then use the SE pass to the CTH.

Yeah I guess I have no choice. Super disappointing I'll keep searching thank you for replying!