Right but i dont understand are there certain heads I cant run through it? terms of ohm,wattage and that sort of thing.
I'm not aware of any manufacturers head that wouldn't be capable of driving your Avatar cabinet.
My GK MB2-500 is...
350 watts at 8 ohms. (One of my cabs.)
500 watts at 4 ohms. (Both of my cabs.)
With a total output of 580 watts at 4 ohms.
The GK MB into my two 210 Avatars, (stacked as a vertical 410), sounds huge and full with lots of cut on a busy stage.
I've seen threads here on T.B. where players have matched Ashdown's, Ampeg tube or S.S., Genz Benz 6.0's...9.0's...Streamliner's...,Trace's, Peavey's, Hartke's, Gallien-Krueger 400RB's...MB 200's...500's...800RB's...700RB's...1001's, Fender's Rumble heads, Markbass LM II's...LM III's, and one player that was running his Walter Wood into a Avatar 210, ect., ect.
At one time you could buy through Avatar, Ashdown bass heads to power their bass cabs, at present your can get a Genz Benz 6.0 or 9.0 or Streamliner heads direct from Avatar.
How many cabs you can run with whatever head you decide on will depend on what the ohmage of your cabinet is.