The Signatures do everything very well. After upgrading from the original C1's to the Signatures I found they sound a little clearer from top to bottom. They also play better at lower volumes. I don't think they play as loud as the originals though which for me is fine.
I currently drive my C1 Signatures with an Octave V70SE. Naim XS also pairs up very well with the C1's. The key is good clean current as Tom mentioned. As for pricing the original C1's retailed for 7K with the C1 MKII at 7.5K and Signatures for 8.5K. If considering any of the C1's make sure to get the Stand4 also.
I currently drive my C1 Signatures with an Octave V70SE. Naim XS also pairs up very well with the C1's. The key is good clean current as Tom mentioned. As for pricing the original C1's retailed for 7K with the C1 MKII at 7.5K and Signatures for 8.5K. If considering any of the C1's make sure to get the Stand4 also.