Hi Dave,
Sorry I've not been on the site for a few days and therefore have only just seen this.
Since you bought the kit a year ago we have produced extra building instructions in the form of Workshop Bulletins, which can be found on Piet's Blog. I assume you are building the standard, manually operated, unit not the Arduino Automated one. Of particular relevance to you are Bulletins 1,2 and 5. If you have already fitted resistors R22 and R26 (100k) in the FET circuit please remove them as they cause an uneccessary DC offset into the following operational amplifiers (Bulletin 1). Download Bulletins 1, 2 and 5, which will guide you through the necessary steps to optimise your eTap2hw particularly in regard to FET biasing and reduction of noise for best sound and signal headroom.
Regarding the FET bias resistors, do not use the 6K8/2k2 combination of drain/source resistors before reading bulletins 2 & 5. If you run into problems I can help providing you were to supply me with 3 voltages and the existing bias resistor values as I have a program written to calculate resistor combinations to get you very close to optimum bias.
Look here for the Bulletins:
http://www.echotapper.nl/wp/Any problems you have please PM me and then we could perhaps communicate by email to get you going.
Steve Mitchell