something that can handle a 1 ohm load....wire the voice coils in parallel and parallel to the amp...deff a mono amp...i had an older ppi pc1400 pushing 3 12'' w6's wired to a 1 ohm load and even though it wasnt a 1 ohm stable amp it never acted up..
You can't get a one ohm load with only two w6s. You can get a 1.5 ohm load by paralleling the voice coils of each sub and then paralleling the subs themselves. Although this is pretty close, one ohm stable amps are meant to really get just that- a one ohm load. I would save some money and try to find a cheaper 200x2 watt amp. If you wire the amp 3 ohm stereo, you'll be giving each sub about 300 watts.