I see the chips are available for sale on Ebay but don’t know if one is bad or even if an other component on the board is causing the problem.
I thought in your original post, that you already knew it was the Accuphase, and that the qualified audio guy narrowed it down to the dac chip (D to A Convertor) chip.
My mistake, as just a swap of the channels would have indicated the Accuphase.
Yes it may not even be the PCM63’s maybe the i/v stage or the l/p filter stage or the output buffer. Yes these card/s house the PCM63’s and the I/V and maybe the buffer.
https://s-media-cache-ak0.pinimg.com/736x/9c/8e/7c/9c8e7ca238a92ee114616a00b3203796--professional-audio-le-son.jpg
As czarivey said $1500 is a bit steep, seeing it’s so easy to remove the faulty card I think in the order of $200 -400 would sound about right, the parts will be no more than $50.
I have a passion for R2R multibit as it’s the only conversion around that converts Redbook (pcm) "bit perfect" all other coverters only give a facsimile.
Better still give it to me, it's 22 years old now and I’m poor and needy.
Cheers George