These comments are in no way a knock on the Sig IIIs as I think they are really hard to beat (my favorites) as an all round speaker in the under $5K range. But they can not compete with the CS7.2s. I think the Whispers by Legacy would be a closer speaker to compare to the CS7.2s. I owned the Focus 20/20 and they are not on the level of these Thiels either.
The Thiels are so transparent its unreal. They completely disappear and all that is left behind is a huge soundstage filled with so much detail it just blows me away. Not only full of detail but presented in a way that you can listen hour after hour without any fatigue. The lush midrange of the Sigs has been replaced with a super clean and detailed midrange that is much nicer. Its as if a thick veil has been removed from my system. The upper midrange and treble with the Thiels is also in a different league. Lots more air and detail. The imaging, and soundstage is were the Thiels really shine. Everything is so solid, big, and lifelike. You can move around the room anywhere, even when standing right in front of one speaker, the performers never move. Its like changing seats at a show. You get a different view to the stage but they never move. I never feel like the sound is off balance (more from one speaker than the other) know matter where I am in my room. Bass is close depending on the recording. Maybe a litle more midbass punch with the sigs, but again not nearly as detailed, clean, or musical bass as with the Thiels.
I was worried that the JC-1s might not be up to the task of driving the Thiels but this pairing really seem to get along very well. I doubt I will be looking to change the JC-1/CS7.2 combo for quite awhile(if ever).
I have upgraded my turntable though. From the Scoutmaster/Karat 17D2 mkII to the Superscoutmaster with signature arm and the XX2 cartridge. I also went from the BAT VK-P10 to P10SE phonostage. I am getting married after the first of the year and my future wife wants a home theater so I need to get my 2 channel complete before that happens. I'm pretty much done except for moving from the BAT 31SE to the 51SE preamp, and will move to a lesser digital source.(one box) Dont listen to CDs that much. Any way, I am as happy as I have ever been with the Thiels and wont let them go without a fight. As good if not better, than any speakers I have heard. At ther new price they are a good buy if you have the power to drive them. Used for under $10K, Very, very, hard to do better. They present "pure music" in a relaxed and completely effortless manor that is to my ears.....the nirvana I have been seeking.