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?