Concerning power requirements. Need high current amp that is easily 4 ohm stable. Your B&W 685 speakers are 8 ohm speakers with 88 db sensitivity. The CS 1.2 are rated at 4 ohm and 87 db. 4 ohm is a much more demanding load than 8 ohm. At minimum you need 40 watts per channel rms with both channels being driven at the same time with something considerably less than 1% THD 20-20Khz; and I'd be looking for something more.
Suitable amplification will likely cost more than the speakers are currently going for.
Suitable amplification will likely cost more than the speakers are currently going for.