All M&K satellite speakers are designed to be used with a subwoofer. The S150THX speakers sound amazing with home theater. I have never heard them with two channel music, so I can't comment other than to say that they definately are designed for use with a sub.
The S150P-THX are the same speaker but with 2 built in amplifiers, one for the tweeters and one for the woofers. I haven't heard them personally, but have been told they sound awesome (though really pricey at $2400 ea).
I'm using the little brother to these, LCR851's and like the way they sound with music.