ok i own a peavey xr-500 and its running into a 215 cab with 1 jack both speakers wired to each other , every time some one starts singing into it compression comes on and baffles the sound , no mater what i do it dont turn off , what can i do to get a louder sound out of it ?

also another question

i got a hartke 2500 amp head , can we hook a mic to that and use it as a pa till i get my hands on something better (when cash permits)
ok thanks , i just figured i'd ask in the QA cause i didnt see anything for pa when i was looking