I have the MB Quart RSD-216's installed in my car right now, and I love the sound. However, some of the highs are VERY high.

Is there any way I can "turn down" the brightness on these speakers? Any kind of setting on an Alpine head unit that might help out? When I want to listen to music loud, I can't really do it because the sound is piercing and kills my ears.

Can anyone offer me some help?

 

honestly.. nope.
Your MBs tweeters are titanium. the pros is that it can handle high wattage and very dynamic with any types of music. the cons is that it sounds a little harsh when you turn them up. warmer sounding amp helps a little but not that much.

 

Check your crossover settings, There should be a tweeter attenuation for atleast -3db. If this does not work, Go into your treble center frequency adjustment on your deck, and push the track up button until you see 12.5 or 15K for frequency on the deck, And turn your treble level down couple notches. This should help. Leave your Q factor alone for now.

Nazar