Just an Idea..

is this possible to have an ep600 amp in the ep500 they seem to have the same driver, for those who space is limited the ep500 format is great but perhaps with a little more power it would make this sub a killer sub they could call it the epc600 'c' for compact or cube

I'm not the best one to answer, but I believe that the DSP of each amp would be optimized for the enclosure size as well as the other factors.

What Mark said. The amp, enclosure and driver of each sub model is specifically designed. The EP500 is already maximized for its size, and it is already a killer sub.

it's like put a big v8 on a small body car, muscle car !!!
may be you just create a muscle sub !!!