It's always nice to have a quick adjustment on the fly when you switch to 5 channel. Take a look at the Velodyne SMS-1 offered here (I also have them at rather unbelievable prices, private message me for more pricing). It allows you to adjust by way of a preset remote control or you can remotely adjust the volume of your sub. No going to the back of it to turn down, no finite adjustments through your AV reveiver or prepro.

In my opinion, this is a must have for any HT.