The Coliseum is a killer amp, but I've never played an Acoustic 150B. I live in Ampeg country, used to live less than five miles from the old Magnavox plant. Since they were arch-rivals in the 70's, you simply don't find vintage Acoustic amps around here. The Coliseum is one of the few s/s heads I like, but if you want vintage Ox tone, you need a tube Hiwatt or the Reeves DR201 copy. The Coliseum has a very tube-like midrange, but its overall sound is geared more towards depth and punch rather than growl. Also, once you hit its volume limit, that's it. It doesn't distort or compress, it just falls out. The upside is that its very loud for its rating, but the Coliseum is more of what I would consider a mid-volume amp.