How much am i comprmising imagining by having my front speakers tweeter 2.5 feet over head (on TV)? in particular the speakers in question are M&K 750s.
You should be able to find an "off-axis' response chart somewhere. Try magazine review websites. Typically anything greater than 30 degrees off center yields a drop of 3 - 10 db in treble response.
Aim them down if possible.
If you like the way it sounds, though, don't worry. Be happy.
aren't most tweeters more or less "straight shooters"? i know they're (in general) pretty directional.
i don't know your particular speaker model, but i think you're probably losing out on some of the higher frequencies. i suspect they may be shooting over your head.
if at all possible, try to place the speakers so that the tweeter is level to your listening position. i bet you'll hear more highs.
i used to have my polk's sitting on the floor. when i got some stands and got them up to ear height i really heard a difference and i'm not one to say i hear tweaks very easily...although i don't have a golden ear either.
anyway, do a test. if you don't hear a differnce then there's no worries.