I don't want to go off-topic more than necessary, but why do you need sub 20 hz output considering that you can not hear below that frequency? Is it just for butt kickers?
What's the better deal here? The EP4k for $279 or the iNuke for $240?
It depends on your needs and wants. I was originally going to buy the EP4000, as it is more powerful across the board. Here are the *RMS* numbers from Behringer, not the peak numbers:
550 wpc 8 ohms stereo
950 wpc 4 ohms stereo
1250 wpc 2 ohms stereo
1750 watts 8 ohms bridged
2400 watts 4 ohms bridged
315 wpc 8ohms stereo
620 wpc 4ohms stereo
1040 wpc 2 ohms stereo
1250 watts 8 ohms bridged
2075 watts 4 ohms bridged
Since I will be driving 2 ohms drivers in stereo, the difference to me is very minimal 1040 wpc versus 1250 wpc. The BIG difference to me is in the power consumption:
2600 watts (does not specify impedance)
350 watts @ 2 ohms
170 watts @ 4 ohms
So, if I am understanding these numbers correctly AND they are accurate, the NU3000(DSP) should draw considerably less current than the EP4000 and make me feel a bit safer that I won't be blowing breakers, especially considering that I am currently powering my 2 ohms per driver sub with 2500 watts RMS (Crown K2 - 1250 wpc @ 2 ohms) and my seven speakers with 2100 watts RMS (Sherbourne 7 X 300 wpc). If this works out, I would like to buy an iNuke 6000 to replace the Crown K2, as the load will be 4 ohms per channel (long story - my other sub) in the future.
Also, if you need and/or want DSP, then the NU3000 becomes a much stronger contender, as it is built into the NU3000DSP, while the EP4000 would need external DSP.
To sum it up, the EP4000 has more power, but the iNuke NU6000DSP is much more efficient, lighter (8 pounds), and has built in DSP - pick your poison...