I was always quite satisfied with the sound from my Thiel 2.7s (spec’d down to 35Hz though probably a bit lower in room). After reading the billionth "you need subwoofers to Have Complete Audio Nirvana" post by subwoofer proselytizers I finally gave in to give ’em another try. (Except for the studios which mix my work, I’ve never heard a satisfying audiophile system with a subwoofer, even when the owner of said system was thrilled and thought the blend "seamless.")
I used some JL Audio subwoofers, their wonderful CR-1 crossover, and some DSP via a Dspeaker anti-mode. The CR-1 in particular was a marvel in terms of increasing the ease of dialing in a subwoofer (and doing really simple "with subs/without subs" at the press of a button comparison).
I got a suprisingly close to seamless blend fairly quickly, though spent weeks dialing things in, playing around, different crossover points, positions, one sub, two subs etc.
In the end I simply liked the sound of my speakers without the subwoofers. First of all, I found the sub rarely added musically relevant sound. And yes, yes I know about how subs also are supposed to "enrich the sound at all frequencies, and also bring more dimensionality and better soundstaging" as they are enhancing depth cues in the bass. I just didn’t find that aspect much better either.
I found my speakers just sounded more coherent, more soild and punchy and dense, and with the exact tone I’ve always loved about them. Adding the sub ALWAYS altered the tone slightly, no matter how subtely I dialed them in, and some of the "magic" went away.
I have no doubt some would have heard the combo and preferred the subs. But not to my ears.
I also did a test with my 23 year old son who listens to my system once in a while. I sat him down and had the crossover box on the sofa near him. I simply told him to listen to some music, and push the button on and off. He had no idea what the button did, or what I was testing. The button simply brought the subs in and out of the system - going between the subs crossed over, to running the Thiels full range.
Turned out he thought it sounded better without the subs too.
It’s guaranteed that subwoofer fans will immediately presume "Well, that’s just because you didn’t dial them in perfectly." That certainly could be the case.
It may also be the case that if I heard your system I’d detect the seams in your sub’s integration, even if you think you had them dialed in perfectly. Maybe not. But it’s happened a number of times when I’ve heard subwoofer sets ups the owner claimed to have "done it right."
In any case, I spent weeks dialing them in, and I have good ears (work in pro sound), and frankly that’s all the work I really want to put in to subwoofers. I’m not interested in making subwoofers a second hobby. So ultimately I sold it all.
And aesthetically it was a relief. I hate the added complexity of adding several subwoofers, the extra cables, especially more AC cables, finding places to put those ugly boxes (I hate the look of subwoofers - never seen a single set up enhanced by them).
So, I’ve decided at this point subs aren’t for me. Maybe I’ll try something else some day long in the future.
(Even though subs didn’t tickle my fancy, the JL Audio stuff is fantastic btw, especially that CR-1 crossover! Transparent and a cinch to use!)