[Alpman]

As long as the four channel amp is 2 Ohm stable, you could run any configuration of 2/4 Ohm front or rear.

 

[Alpman]

There should be 2 Ohm and 4 Ohm ratings in the spec sheet. Just throwing some figures out there, so if the 4 Ohm rating is say 75 watts X 4 and the 2 Ohm rating is say 150 watt X 4, then you would be running 100 x 2 to the front and 100 watts X 2 to the rear for a total of 350 watts.