@rfprice The 125XD was what I was thinking of getting at first because it was cheaper. However, I was able to do a trade-in for the 175XD. If I was able at the time, I would have bought the used 300XD that I linked to.
The number in front of the XD represents the number of watts. So, 125, 175, and 300 watts of Class A. Now this is the iBias Class A that I think sounds amazing.
My 175 sounds better than the 90 in my old K-300i integrated but that is really not an apple-to-apples comparison.
With regards to the DAC. I strongly suggest you try the LA4 preamp in front of your DAC (30-day trial). I am almost certain that it will be better than DAC direct to amp, even if your DAC had more power to drive an amp. The pre is small in size and the quality of sound compared to DAC direct was really easy to hear. This is especially true at low volume levels.