CD distortion through preamp


I apologize for the long post. I’m trying to make this as brief as possible while providing all the necessary info.

The equipment: preamp is Audio Research Ls25 mkii, pass x250.5 amplifier, and bryston Bha headphone amplifier, Wilson watt puppy speakers. All connected with balanced cables. I needed the fixed output to rip records, so the headphone amplifier is connected to the 2nd variable output.

The issue: I’ve had problems with CDs distorting when the music (dynamics within the performance) gets louder. The distortion is mostly noticeable in the mid to upper range and it’s through both the speakers and headphones. No issues listening to records or dac when it is hooked up to the computer with usb. But when I tried using the CD player as a transport to the dac, the distortion returns.

here’s what I’ve tried without success:
-new tubes in ls25
-3 different CD players
-tried rca cables
-different inputs

I also tried a Bryston bp25 solid state preamp and had no problems. It seems like the ls25 is the issue. 

Any thoughts or suggestions?


tripg

Showing 5 responses by tripg

Mike_in_nyc, you are correct. there are 3 gain settings for each input. I have the CD player on the lowest setting. I’d think higher would be worse, but I’ll give it s shot to see what happens when I do. 
Twoleftears, I’ve tried a few different inputs, but didn’t think to try using the dac or phono preamp’s inputs. I’ll check that out. Thanks!
Al,
To clarify, both the amplifier and the headphone amplifier are connected with balanced cables, not rca for amplifier, and balanced for headphone amplifier. 
With my little knowledge of impedance, I would not have thought it would be affected by connecting 2 amps. I’m interested to see if that makes a difference! Thanks!
Mike_in_nc,
if I understand you correctly, I don’t think it works that way. When you raise the gain setting from lo to med or high the volume definitely jumps up a notch. 
Al,
you were correct!!!!

And looking back, it makes a lot of sense.

I haven’t always experienced this issue and I’ve been using this preamp/amp combination for years. I switched the headphone amplifier to a variable output about a year ago. If I had a better memory, I’d likely recall that’s when the problem started. Although I still think it’s odd the DAC didn’t distort like the CD player. I’d think their outputs would be the same. I’m just happy it works correctly now!!!

I can’t express how grateful I am. Thanks AL!!!!

Luther