The subwoofer control even has a mark for the THX setting. The headphone jack is standard fare, but the line-in is a very useful innovation. It is an input for portables such as an MP3, MD, or CD player. Sorely missing on the preamp is a power switch. Klipsch decided to mount it on the sub, which was dumb.
Man is that silly.
In a word, incredible. I used the 2.1s for music, movies, and games. In every instance the system was both dynamic and comfortable. The older Klipsch systems sounded good, but the 2.1s are probably the best sounding desktop speaker that I have used. The claimed wattage is definitely not exaggerated.