PA2 doesn't have a digital path through it, so analog inputs are converted to digital, processed, and then converted back. There's no way to avoid the ADC/DAC cycle, which means whatever distortion and noise it adds will be added on top of whatever is there at the input. Now, these may add up in different ways, but ultimately, if you put in the output of a DAC that's fairly clean, say 120dB SINAD, you'll likely get, at best, a 94dB SINAD out of PA2. Not that this is a poor result by any means: it's better than most amplifiers can deliver. Some newer dbx models allow all digital processing, without the analog conversion. So you could use a really good DAC after the unit, if you feel that a very high SINAD is a must. Personally, I wouldn't worry about it.