i have recently bought a behringer BX4500H amp head. it's 450w and has a min load of 4ohms. i want to run it through an old 18" speaker cab that i have. it's an acoustic 301 transducer (very old i know). i've had it for awhile now and really don't want to part with it (i like the sound, and funds are tight). i've always played an old yamaha amp through it, that i got off my mate years ago. that's 250w with min load of 4ohms. i've just found out that my speaker has an impedance of 3ohms, but no idea what kind of max power it can handle. my new amp worked for a bit, then just started buzzing when i switch it on. i thought i'd wrecked my speaker, but testing it with the old amp, it's fine. I'm clueless when it comes to power ratings, impedance, etc. what can i do? do i have to send my amp back? or is there a way of making it work with my cab?