The QS10s will get you down to 50Hz or so, maybe even 40Hz. Modern surround formats carry signals down to 20Hz. The convention is to send whatever bass the speakers can't handle to the .1 subs. I've discovered however that bass from its own channel and the .1 subs handling just LFE, results in a more nuanced soundscape.
My current setup is 4.1. My fronts are full range because I have dual 500s off DSPs. To make my sides full range, I plan on situating a 500 below each QS10. A speaker cable will bring the QS10 (high level) signal into the 500. The 500 will replicate the information below 80Hz sent to the QS10. This way, I will have true 4.1.
There's more to this unconventional plan. In addition to the four 500s, I will have two 600s and an 800. The two 600s will be in the back. The 800 will be front and centre lying down. These three will handle purely the .1 LFE during movies.
But it gets better. During two-channel music, the two left 500s will handle the left channel bass. The two right 500s will handle right channel bass. The 600s and 800 could be put into what you call LFE+Main or Double Bass as it is known on my Onk.
So in summary, 7 subs to allow true 4.1 with the ability to use all subs for 2-channel.
