Is my amp the problem?

Class D's are fine for subs, but even the best ones are pretty poor in the upper mids and highs.  Also, It is FAR better to use a good stereo amp than to biamp with dissimilar amps.  Biwireing is good, biamping is not.

That power supply is pretty hefty. The specs are 4.16 amp if you are doing the +12V DC model. This is fine if you are powering a several items like the miniDSP (which is very low current draw and uses basic op amps).  It's fine even for adding Antimode 2.0 into the mix.  This power supply has a lot of capacitance.  The capicators they use could be better, but the price is right for what they give you.  If you need a split power supply (i.e. +15V / -15V), then you'll need a different power supply.

Stringreen what Class D amps have you heard and what are you comparing them to?

thanks.

Have not heard that exact amp but have heard Crown Class D amps at the gym and I own other Class D amps.

One thing is all Class D amps have very high damping factor including that one and the ones I use. Good ones do bass in particular extremely well, better than most anything else. Hence their popularity for use in powered subwoofers. When I first heard mine, I thought bass was gone also in comparison but turned out to just be more dimensional, articulate and clean in stark comparison to prior which was more towards stereotypical "one note" fatter bass which many may be used to and may seem like more or better but is not IMHO.

Stringreen, I have been told the same by other people as well. I am too far down the road now. Maybe in the future I'll reconfigure. I  have been fine tuning it and it sounds pretty good right now. Still needs more impact but I have some options.