The UMC1 replaces LMC1 and the XMC1 replaces MMC1
the XMC1 will have a better processor and more options than the UMC1... so I've heard
Just like the first generation
As for the Xpa2 it has no pro reviews yet. However I can tell you that my Xpa5(its brother) is incredible. I use it to power my m80's qs8's and vp150. I have never had a problem and the sound is Great! When i use it for just stereo to drive the m80's the bass and overall accuracy is amazing. I would guess that when run in stereo it is similar to what the xpa2 would sound like..Minus a few watts of course
