i'm guessing meaning going active right? in the active world this is very common and this is called "DIY." meaning mixing and matching speaker brands to fit the sound that you like. i mean i have mixing speakers right now: lotus 8, lotus 4, and rainbow cal27 running my front stage and i love it //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif.
i would highly suggest if you going active, do some research at diymobileaudio.com. if you can't audition speakers, try to read as much as possible over there to find out what kind of sound you like. there are numerous threads about specific speakers and its characteristics.
the places that diy speakers are sold at are partsexpress.com, madisound.com, solen.ca. there are others as well.