I'm far from a techie....so im just looking for some advice.

Is there any reason I shouldn't use a Mackie Power mixer PA to run my 2 cabs? I run a bass cab 115 and a slant 4x8 guitar cab. I don't need an eq because I run a Tech21 character pedal. Only other pedal I run is a big muff.

With this setup I get the tone I want (kinda like Pepper Keenan and Dimebag but it's mine)but I'm not sure if I'm gonna ruin something. Thanks!
As long as the impedance of cabs matches what the powered mixer expects to see, I don't see why it can't be done. The powered mixer doesn't care if you're powering a cab, or a proper speaker, just as long as the impedance and wattage handling are correct.
as long as the Ohms match and the speakers can handel the wattage then you'll be fine.
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