I have the Monitor Audio R90 AV speakers (4 x R90 and 1 x 1R180). I now want a matching subwoofer for the system. The one I'm interested in is the REL stampede, however, there is one problem. The REL's upper frequency response is up to 99Hz. On the other hand, I've read the Monitor Audio speakers's lowest frequency may be up to 125Hz. My concern is that there will be a gap in the frequency response? Would there be another subwoofer more suited to these speakers? What about the MJ Acoustics Ref100? How does this compare to the Stampede? Thanks.