Well since amps really arean't optimized for 8 ohm loads youll basically be wasting half the power the amp is capable of, however the amp will run cooler at 8 ohms than 4. Youll need an amp that is rated for around twice the power of the speaker because you are running it at 8 ohms (it was probably from a pair so they could be hooked up for 4 ohms). Id look at something in the 250 -300 at 4 ohm watt range and that should be fine. I had a single 8 ohm 10 running off 240 watt and did the job fine for me but im not a bass head. What price range of amp are you looking at?