Using a CS 3 eq with the 3.5's would be better than not using and eq. The CS 3.5's eq adds a switch that toggles between boost for bass extension into either 20 or 4o Hz. The CS 3's eq does not have that switch. As I understand it the the the CS 3.5's eq was a cleaner better sounding unit that eliminated caps from the signal path. You might get a better, more accurate response if you posed this question on the "Thiel Users" thread here on Audiogon, as Tom Thiel often generously contributes and fields specific questions.
