Which Sunfire Sub for my Magnepan 1.6's

Among the Sunfires, the Signature goes deepest and can provide the most volume. This may be more than you need to complement the Maggies for music. For home theater, they would be a good selection. I have two in my main system which does double duty for music and home theater. The Architecturals have a slightly more stylized cabinet and only the one low frequency driver, designed to be used in a front facing installation like an in-wall location. The regular Signature probably goes louder and maybe a little lower with the passive radiator working opposite the driver.

At the other end of the range, the True Sub Juniors don't really go all the way down with any real volume. They are often chosen for installations where size is the paramount consideration. I use one in my library, improperly located on a bookshelf (yeah, I know -- feh). They do ok with mid-bass material, where many listeners develop the impression of bass presence.

In the middle, the True Sub Mark IIs may be just the ticket to go with your Maggies. They go almost all the way down, beginning to taper off somewhat above the low end of the audible range, but not so that one might really notice with regular music. They should provide adequate volume to go with the Maggies, without overkill, for music material. They probably won't be quite satisfying for dinosaur footsteps, though. I have one in my sunroom system supplementing a pair of stand mounted monitors (no home theater). Good luck.

The True Sub Mark IV is the current version of the Mark II. Sorry I'm a little out of date. In my opinion, the Architectural Signature might be a little more than you need, unless you're really into big bass. If you get it, you should certainly have the low end covered. Personally, I think its better placement flexibility (versus the driver/passive radiator regular version) can be a meaningful advantage depending on your room. If you later upgrade your main speakers, you might feel good about not having to upgrade your sub.

I have found that a good number of Audiogon posters prefer REL subwoofers, generally described as more tuneful -- better able to distinguish different bass frequencies. I once had a REL Strata II which was OK but didn't bowl me over. I am told that the quality steps are large between REL products, and the bigger ones are much better.

To me the Sunfires sound good, within the parameters I described above. I haven't really found them to be afflicted with rubbery, boomy resonances, as some others have complained. Perhaps room and placement are big factors here.

I like Bob Carver as a designer. As you may know, Bob has been controversial in high end circles for decades, beginning with his "Carver Challenge" in early Stereophile pages. I think he has gotten better over time. I regard the Sunfire subwoofers as cool products that are manifestations of at least two novel technological advances (in drivers and in amps), although copycats (or OEMs?) have appeared in recent years. For what it's worth, the Sunfires have received generally (if not unanimously) favorable reviews in the audio press. Good luck.