Accuphase dac 60

Since Accuphase apparently designs their devices for the same voltage whether balanced or unbalanced, you might try the unbalanced output from the PS Audio DAC for closer comparison. 

Are the optical and coaxial digital inputs two different sources?

Also, how is your Sub connected?
 

@duketbrd88 

I noticed that your amp has “Individual phase setting for each input”, so you might try that to see if it helps. 

Does your music source have an attenuation you’ve used in the past to equalize your PS Audio DAC to your other sources?