It's a bit expensive, but the SMS-1 would provide a dedicated remote sub volume control and would be an excellent way to integrate the sub with the rest of the system - to the point where you might find your volume tweaking days behind you. In fact, some of that tweaking may be the result of you trying to compensate for a null or peak under 80Hz that is obscuring sounds at other frequencies...

We all take different approaches to how we set up and use our systems, but I've always tried to find a way to get the sub integrated with the mains such that the two blended without the sub calling undue attention to itself or being left out. By being able to set the crossover point so that my mains handle everything down as far as they can effectively go (as is possible with the 990's quad crossover system) and tinkering just a bit with my sub trim, I was able to get my LFM-1 to blend quite well with my Paradigm Studio 60's prior to getting the SMS-1. Once I had the SMS-1, I actually raised the crossover so that the SMS-1 could correct for a problem spot at 63Hz. Being able to use a test tone to achieve both flat frequency response across the sub's full range of activity and equal level with the mains is really the ideal for sub integration. That's just me, though, and what works for me won't work for everybody.