bad pyramid amp?

I recently started to have a problem with my system . I have 2 10" pioneers subs and i think they are 300 watt rms and i have 4 8" subs from some company called audio works. I had a pyramid amp 500 wat rms running them ( its only a 2 channel). They were running perfect for about a month until one morning i went to turn them up and all i heard was a very loud humming noise from them and there was no music. I looked and they were moving like crazy so i un hooked them and re hooked them, they were working until i turned them up and it did the same thing. I have a good set of wires i think they are 8 gage and ive tried different   a different set of rca's and a different ground spot with no luck , does anyone have any info that would help me solve this problem, thanks

Isn't "bad Pyramid amp" an oxymoron?    Yes, sounds like your amp died, unless you have recently changed the gain setting.  I recommend purchasing a mainstream brand this time.Support the12volt.com

thanks , that amp came with my speakers but what brands are good but not too expensive?

What's your budget?Support the12volt.com

im only trying to spend around 150

OK, well unfortunately at that price point you are looking at the low end indeed,  You might be able to pick up something on closeout or maybe a factory refurb.  Check with your local dealers.  Avoid Pyle, Pyramid, Performance Technique, Volfenhag... at your price point some people have great success using Power Acoustic or Boss.  But if you can find a decent Kicker or MTX or Rockford on closeout you'll be better off.  And don't be hung up on power ratings.  Just get the best brand you can if you want it to last, and set it up properly.Support the12volt.com