Time for someone else to throw in their .02 worth. I also have the Mini Monitor v5's, and my music/HT split is about the same (music is mostly rock). I have the Mini's paired with a HSU STF-2 ($380-ish shipped). I absolutely love it for music, crossed over at 80 Hz through my Marantz SR5003 it blends extremely well with the Mini's (set to small of course). Definitely doesn't muddy them up; in fact, it frees up the Mini's from having to reproduce the bass, which I'm sure you've noticed they aren't too great at.
Let's put it this way: I'm upgrading the Mini's to Studio 20's before I'm upgrading the sub. (Also, the Mini's should be great as surround speakers; that's a plus.) The STF-2 is no slouch for home theater either, as long as this isn't too large of a room and you aren't an SPL nut. Music is definitely its strong point though.
I don't think I'd spend the money for Rotel separates at this point (well duh; I obviously didn't
). The Marantz SR5003 I have seems to cut out a bit of the harshness the Mini's tend to have, and imaging seems a bit better. I honestly didn't look into receivers a whole lot; I just heard that Marantz was good for music, and saw that their SR5003 competes features-wise and price-wise with Denon, Onkyo, Yamaha, etc., so I went for it. (Rotel and NAD were out of my price range too.) Plus, I wanted 3 HDMI inputs, and the ability to decode DTS-HD and TrueHD onboard is nice. Plus the Audyssey MultEQ is a convenient feature to have.
Well those are the things I went with. The SR5003 seems pretty future-proof at the moment; 90W x7 is plenty of power, plus it means I can passively bi-amp the Studio 20's and still have a 5.1 setup. MSRP on it is $800, I found it for $640. That, plus the $380 for the STF-2, and you're at right over $1k. And you still have $500 or so for new sources if you want. (Personally an HTPC is my source for everything but Bluray; a standalone Bluray player is probably in my future.) Just an option I'm throwing out there since I'm very happy with how it turned out; I'm sure you've found lots of other options too. eD, SVS, PSB, Velodyne all make competing products with the HSU sub; most of those are more geared towards HT use from what I've read. I would recommend going for a bigger sub if you listen to a fair amount of rap or techno, have a larger room, and/or watch a lot of action movies where you want to feel the bass.