A TRUE reference LFE channel is hard to find. The best is the PMC XB-3. This is the sub most truly serious mastering and recording facilities use. Most of the recent large scale movies are recorded and mastered with the big PMC systems and the XB-3 is the LFE channel of choice. Nothing else really comes close. It is big, it is expensive at about $11.5K with a Bryston monoblock amp, it takes about 2 months to have one built...but it is without parallel and has credentials that no other LFE speaker system has.
Beyond that...the James EMB-1500 is damned impressive in our showroom, besting all comers below the big PMC's.
Beyond that...the James EMB-1500 is damned impressive in our showroom, besting all comers below the big PMC's.