Bright would be like heavy treble emphasis in overall tonal balance, vs. dark being more murky and bass heavy with, relatively speaking, a more recessed treble.
Haven't heard Mirage speakers in years, but based upon reviews I've read in past, those are what I would consider a substantially more dark tonal balance.
An internet only option you might consider other than the Klipsch are Hsu HB-1 mk. 2:
http://www.hsuresearch.com/products/hb-1.html (kind of like Klipsch in that they have the darker, weightier overall tonal balance, but perhaps have a more refined treble that isn't as coarse and ragged as I think Klipsch can be).
If you are heavily more home theater and gaming centric than music, also go to Best Buy and take a listen to the Andrew Jones designed Pioneer speakers (SP-FS51-LR or look on internet for SP-BS41-L-R). Google in Hot Deals forums for some great deals that show up from time to time at Newegg. Just breaking in a set myself, but I'd say they fall somewhere in between Klipsch and Hsu (similar weighty type tonal balance as Klipsch and Hsu, but definitely more crisp treble than the Hsu). Slightly on sale this week:
http://www.bestbuy.com/site/Pioneer+...0c21&cp=1&lp=1 and
http://www.bestbuy.com/site/Pioneer...917&skuId=1147943&st=pioneer sp c21&cp=1&lp=1 If you didn't already own a sub, the matching Pioneer SW-8 would probably be fine in that room with other Pioneer speakers (on sale at Newegg for $80 shipped often). Some comments I've read online say it's an 8 inch "subwoofer" that sounds like a strong 10 inch subwoofer. Your Klipsch has a 12 inch driver, so it should have lower ultimate bass frequency extension and play at higher absolute spl capability, but if you live in an apartment or condo with shared walls with others who don't appreciate rattling walls, the SW-8 might fit your current needs quite well (at least unless you really don't mind annoying your neighbors alot), and especially if you get the matching Pioneer front and center speakers.
If your budget is flexible, then you can go listen to some entry level hi-fi and much higher at
http://www.gcaudio.com/products/lineList.html (Ft. Worth area)