Frequency response and noise, crosstalk and signal to noise....Gotta take the faceplate back off and dis mount both boards. ..I had forgot to bypass the power pins on the new op-amps. Joe's recommendation since we started putting in the latest generation op-amps is to put a .047uf poly cap accross the power pins. cleans up the power supply going to the op-amps. AND the led goes to the faceplate BELOW the board. Jeez. We'll be testing in an hour...