I used my Ashdown ABM 500 with Ampeg cabs a couple of times. Did not like the sound one bit I'm sad to say, they didn't seem to match at all - the Ampeg cab seemed to turn the Ashdown into a load of undefined mud. And I had the amp set to a very trebly grind!
I was always very happy with Ashdown cabs, unsurprisingly, but the best match I ever had with that amp was an ancient Mesa Boogie 1512. I've never heard a tone quite like it.