I have experienced good results with various REL subs with the Aerius i, when using the power amp's speaker terminals for driving the sub (and so no preamp problems for you). This is in fact the method recommended by REL. The other feature with REL is that you do not have to feed the signal though a cross-over to feed the satellites, which normally degrades the mids and highs. Instead you use the Aerius full-range and just use the REL to do the deep bass. For the Aerius I recommend you start with the lowest low-pass setting on the REL and then bring the level up until the deep bass is in balance. Then try higher "low-pass" settings to fill any gap. But before you start playing with any sub, you should always work on getting the tightest bass you can out of your Aerius speakers. Subs cannot turn bad bass into good bass, and no sub can be successfully matched with bad bass in the satellite speakers. One important thing to do with the Aerius is make sure they are absolutely rigidly mounted on the floor. Any movement destroys the sound with these speakers. You may find that very rigid mounting makes the sound a little strained. Do not worry about that because you will find that adding the sub will make the sound breathe again.
