Some time ago TAPR did a one-time run of a very low noise, very high isolation buffer amplifier. The assembled boards are sold out, but we had some extra blank boards made and finally (after a long story) got those delivered from Hungary to the office. If you're interested in a TNS-BUF board, they are $15 plus shipping and you can order via the button at http://tapr.org/kits_tns-buf.html I'm working on a publishable bill of materials for the parts to stuff the boards, and will put a link to it on that web page ASAP. John