i have built a Ratt Deluxe but you need a very high input level (line level MP3 player, guitar with a boost full up in front) to be able to hear an output. The knobs seems to work fine (hiss increases when turning up filter, overall noise with Gain and Vol).
Something seems to be wrong, I checked the soldering connections, directions and parts.
+1 the (T) is for Tip in its audio path destination and the other pad is conveniently located to provide a short ground to the In and Out jacks to avoid star grounding. We have designed the boards to be built in 3 of the most popular build fashions (on a single board) so there are many options however the (T) for tip (See wiring diagram) is a must and probably the only issue.
See Pages 5, 6 & 7 for complete details including a “Standard Wiring Guide” from the official GuitarPCB Crash Course Guide
Incidentally this guide and many others can be found on our Guides Page which can always be found by clicking on the GUIDES button on our home page or the large RED button at the bottom of our Forum Home page as well.