I don't have any personal experience with the Sunfire unit, but have read several very positive reviews and can't imagine it's not at least "good" with 2ch music. I think it's when you want it to be "great" that you might run into problems. "Great" tends to cost a lot of money, as we all know, so ultimately upgrading the pre/pro in the pursuit of great sound may not be that daunting a proposition. No question, with the technological advances in progress and on the horizon, HT in particular is an area that you have to expect to upgrade on a fairly regular basis
All that said, I agree with Tim's advice on the HT-pass-through functionality as a practical way to use one system effectively for two different purposes - he's given you good advice in that regard, since the approach offers the most flexibility down the line. However, as much as I love great audio performance for music, I love it for movies as well, and I'd be willing to bet that a lower-cost Denon receiver for HT will be markedly less performing, and therefore less enjoyable, than the Sunfire for movies and I personally wouldn't be willing to make that sacrifice permanently. You don't give a lot of context for your question, and budgets etc. factor in a great deal, so if it was part of a bigger plan, an affordable Denon A/V receiver coupled with a nice two-channel preamp with HT pass-through might be an excellent start, but if you're really into doing HT right, you're going to want something better than the Denon long-term. -Kirk