13yr old speaker upgrade

Monitor Audio Silver towers (the bigger ones) and matching center. Or at lower price point, PSB Image towers (the bigger ones) and matching center, more left over for your amp.

Even by today's standard, the DM604 S3 is still a very good speaker and worth decent money used, however not much with one not functioning properly. Crossovers rarely fail. What is the sound coming from the speaker? Just guessing, I'm wondering if by going to a larger room with the system, and if you occasionally play it loud, then maybe a blown tweeter. Does the speaker sound dead, like a blanket is covering it while playing? Even if you want new speakers, it should be worth repairing the DM604's.

I'll echo what Tls49 said, but do you suspect the crossover b/c you're not getting any sound output from the speaker at all? If that's the case, I'd first check to see if your speakers have any fuses (possibly a dirt simple fix)...or, if it really is the crossover then there are plenty of very reputable HiFi repair companies out there that could easily and rather cheaply do that kind of work. All you would need to be able to do is to find a way to reliably uninstall and reinstall the crossover to allow you to send it in for repair by itself (MUCH cheaper than shipping the whole speaker). But even if that was out or the speaker was otherwise effectively dead altogether, unless you're just itching to try something new, I'm supposing you could always just buy another (used) pair of the DM604's and the one you have left over now could be your center tower, if that works for you (and the center tower is not going to be too tall for your app, assuming you're not needing to go horizontal with it). Or if you have any HiFi shops within driving distance you may want to see what you might arrange to audition, or even borrow if the dealer can be worked with (just be sure not to borrow anything you can't afford ;^) But, even if all that's out, then I do believe I'd second the Monitor Audio Silvers as well.