is it possible to connect external tweeters to current speaker setup? I would like to have better trebble in my system without dishing out for a whole new setup. How woudl i go about doing this?

my setup include:

HK AVR130 receiver
2x MTX Monitor 12
2x MTX Monitor 10
1x MTX Monitor 6c
Velodyne CHT-12

The low end sounds great to me, but the highs could be a big sharper.

Any suggetsions? Thanks!