Welcome to this little corner of the 'net, mzpro5 and Big Red Machine. You certainly popped in at an interesting time - I suspect this it just the beginning of the many discussions we'll be having here regarding which is a better choice between teh 970 and the 990. It'll probably take a month or so to get enough first-hand feedback to move the debate beyond theory, but there's already some pretty useful information floating around to help folks make up their minds. Mzpro5, if you happened to already have an old receiver to handle patio duties and didn't mind spending a bit of money on a decent phono pre-amp, the 970 could be a good fit (especially if the 2.25" of extra space behind the unit helps you out), but if you can handle the depth and the MM phono section works with your turntable I suspect the 990 would put quite a smile on your face. For me, the added depth wasn't too big a deal - I'd already had to chop the back off my cabinet for the 950 (even though it's not even as deep as the 970) so I could have access to the rear panel, and I just enlarged the hole a bit. It actually gave me a reason to clean up the cut. Your mileage may vary in this regard, though.

That MP3 support is probably very rarely implemented - you have to have a way to get MP3 files to the chipset, and that's not a real easy process. DVD players generally decode MP3's internally and output PCM, and while the 990's USB input acts as a USB sound card I'm still pretty sure from my experience that the MP3 decoding happens at the PC's media player. You could build in an ethernet interface of some sort so that the processor becomes a network media client, in which case the MP3 decoding would be quite handy, but otherwise I doubt it's very often used.