I've just purchased a MX121. It's fabulous for movies and is a big upgrade over my previous Marantz 8003. For music though, the D100 DAC + C2300 preamp is superior. I'm hoping to try the D100 with the MX121 this weekend and see how that compares to the D100 + C2300 combo.

If you're not bothered about the latest and greatest (Atmos, etc) or your wife won't allow more than 5 speakers in the room where you have the MX121 I say go for it! Also looks great next to the rest of the Mac gear.