Mirage S-10. I have been using its predecessor, the LF-10, for 3-1/2 years in a 2.1-channel music-only system. It's a front-firing 10" with dual ports, 150w internal amp with 400w peak power, continuously adjustable output, continuously adjustable crossover from 40Hz to 120Hz, and a 0-180 deg. phase switch.
I mention all this because the Mirages are exceptionally easy to blend with satellites. I've placed Mirage subs in two of my systems and also in a sat/sub 2.1-channel setup in my neighbor's living room. The Stereophile test CD demonstrates that these subs extend down to the mid-20s.
In the 3-1/2 years I used this arrangement, the Mirage sub was unfailingly musical and lively, blending seamlessly with the satellites. It never sounded like a home theater LFE "thump machine" sub, but always supplied an agile and timbre-correct foundation to the music.
And I played every type of music with this setup--folk, acoustic and electric blues, acoustic folk, acoustic jazz, big band, orchestra, chamber music, pop, rock, opera, bluegrass, electrified country, and choral music on SACD, CD, and LP.
I recently replaced it and the sats with a pair of full range floorstanders because I wanted to increase the overall radiating area to fill the open-architecture living space better. HOWEVER, I can't say that doing so particularly improved the bass-to-midrange continuity over the Mirage sat/sub arrangement. Either I'm uncommonly lucky or they're that good at blending musically.