John ... I use my Podium 10's with an alesis fx6 mixer ...when I used them in a stereo set up they sounded great ... this past week I had a small gig and used just one through the mixer and also experienced the same thing as you - a very treble, even sharp tinny, sound ... I cut down the mid range control on the speaker to the negative side and it sounded fine ...
Almost forgot - I tried using a 'Y' cable coming out of the left and right on the mixer going into the speaker ... I think I was somehow 'overloading' the speaker using this set up, because when I changed to just the left out of the mixer into the speaker it sounded much better ...
hope this helps ...
t.
[This message has been edited by tony mads usa (edited 10-20-2009).]