It's hard to say, since I heard them in two different systems, but they are very very similar. From what I heard, I'd say they sound almost identical. The bass on the TC70 was maybe a hair tighter, faster, but I heard the TC70 w/ Linn Klimax amps and that could've been it. I also felt the TC70 imaged better. If I had a choice on the used market, I would've chosen the TC70. Would I spend the $8K for the pair now on the 'gon? Not sure, probably would. I was seriously considering coughin up the $12K my local dealer wanted. Although maybe the C8 is better in a larger room, which I have. I do love the C8LTDs a lot. They sound amazing as did the TC70s. I think the TC70 are smaller in size, and their cabinet are made from one piece of aluminum, which is pretty amazing. Pretty sure they use the same tweeter/midrange unit. I had one of the tweeter/midrange units replaced on my speaker (still not sure when/where it happened), and Piega sent it to me and I'm guessing this is the same driver they're using now in the TC70x and other speakers. If you do get them, I would drive if possible to pick them up to be safe, and check the drivers closely, box them up safely in the original packing if possible.