I've heard and implemented a fair number of subs with both stereo and 5- and 7-channel surround. I have four subs active in my house right now and implemented two different subs over time on my neighbor's 2.1 system.
Based on the subs I've heard, if you can afford the JL f113, get it! Bear in mind that as good as a single JL sub is, two are better. I heard a setup of Maggie 20.1s flanked by a pair of JL F212s and the integration is seamless.
If you're doing 2.1, especially with something that can handle the dynamics and power handling of your Dynaudios, don't obsess over sending a high pass signal to the Dynaudios. You will get a smoother, more musical blend if you simply let them run full-range and use the sub(s) to fill out the bottom octave with the sub crossover set at 30-50 Hz depending on the speakers' capabilities and the room's acoustics. The C4s spec down to 27 Hz and power handling is rated at 400 watts. They're big boys designed to handle full-range signal even if they don't give you all the sub-30 Hz output you're looking for. When you're adding a sub to mini-satellites with 4-1/2" woofers, a high pass filter makes some sense, but for C4 floorstanders, not so much.
In home theater I *do* use high pass to the surrounds, but that is for handling the dynamic range of effects soundtracks--explosions, crashes, etc. For a musical blend, you're better off not adding yet one more network filter to the signal sent to your mains.
Given SVS's 45-day eval/return period and one-year full-credit upgrade program, you might want to start with a pair of SVS's and see if they give you what you want. One nice thing about the SVS's you're looking at is that you can choose any one of four different low end rolloff profiles depending on whether you leave all three ports open or use the supplied plugs to stop one, two, or all three ports. You may find that plugging all ports gives you a smoother low end curve and more ultimate extension for music.
I have a friend who uses the sealed compact SVS with his Maggies and he's very pleased with it.
Based on the subs I've heard, if you can afford the JL f113, get it! Bear in mind that as good as a single JL sub is, two are better. I heard a setup of Maggie 20.1s flanked by a pair of JL F212s and the integration is seamless.
If you're doing 2.1, especially with something that can handle the dynamics and power handling of your Dynaudios, don't obsess over sending a high pass signal to the Dynaudios. You will get a smoother, more musical blend if you simply let them run full-range and use the sub(s) to fill out the bottom octave with the sub crossover set at 30-50 Hz depending on the speakers' capabilities and the room's acoustics. The C4s spec down to 27 Hz and power handling is rated at 400 watts. They're big boys designed to handle full-range signal even if they don't give you all the sub-30 Hz output you're looking for. When you're adding a sub to mini-satellites with 4-1/2" woofers, a high pass filter makes some sense, but for C4 floorstanders, not so much.
In home theater I *do* use high pass to the surrounds, but that is for handling the dynamic range of effects soundtracks--explosions, crashes, etc. For a musical blend, you're better off not adding yet one more network filter to the signal sent to your mains.
Given SVS's 45-day eval/return period and one-year full-credit upgrade program, you might want to start with a pair of SVS's and see if they give you what you want. One nice thing about the SVS's you're looking at is that you can choose any one of four different low end rolloff profiles depending on whether you leave all three ports open or use the supplied plugs to stop one, two, or all three ports. You may find that plugging all ports gives you a smoother low end curve and more ultimate extension for music.
I have a friend who uses the sealed compact SVS with his Maggies and he's very pleased with it.