Valinar makes a good point that in a your relatively large room, perhaps the 40.1 is the better choice. But if you stick with SLH-5, a pair of JL F113 should be plenty -- provided you split the signal and relieve the SLH-5 of the bass work. If you have spoken to JL Audio, you know they strongly recommend crossing over to relieve the mains of the work that is the sub's specialty. True, integrating subs can be a challenge, but it is doable; and when done right, its terrific. Also, integration is far less difficult when using a cross-over, rather than having the mains rull full range and overlapping the sub in the mid-bass.
