I have the ProAc sub and have generally been very happy with it with one exception. The lowest x-over frequency is 60Hz, which was too high with my Audio Physic Tempos. I was able to correct with my TacT 2.0 digital correction equalizer, so my story had a happy ending. My guess is the 1-SC will be fine with a 60Hz x-over point. I found the sub to be up to the task of both music and home theater in my small/mid size room. I have not heard the RELs at home, but from the auditioning I have done, it seems like the REL and the ProAc are very close in their musicality, but the ProAc seems like it can move more air before sounding strained than the REL. I don't think you'll go wrong with either one.
What do you know about the Pro-Ac Subwoofer?????
Well I've got a Velodyne ULD-15 and I thought that a newer designed subwoofer might be better. The ULD-15 sounds kind of muddy. I don't need a lot of volume ,but just good bass.I would be using it with a pair of Pro-Ac 1-SC's. Let me know what you think......Will