Loop Return Ground Scheme
The Return jack sleeve connection is not connected to signal ground. This prevents ground loops when using the second stage as a loop, and prevents the cable in the loop from acting as an antenna for RFI and noise. This works in both parallel and in series modes, with no loss of signal under normal operation.
However, you may find that you either lose signal completely or there is a lot of noise when you activate the loop. This will generally be an indication that you are using a bad cable, or one where the ground has been disconnected. Replace or repair the cable and retest.
In the very unlikely event you have noise or a loss of signal when using the loop, and you have tested the cables involved and found them to be working well, then read these instructions on modifying the Loop Return ground scheme:
Modifying the Loop Return Ground Scheme
Carefully remove the four stainless steel screws on the Triad and gently remove the bottom cover. On the bottom of the circuit board there are two holes vertically aligned in the middle towards the edge where the jacks are:
One hole is connected to the Return jack sground, and the other hole
to signal ground. You can bridge these with a short piece
of wire and then solder the wire to the solder pads surrounding the holes.
This will tie the Return ground to signal ground but at the cost of possible
ground loops or RFI being introduced into the signal.
Please do not attempt this if you have no prior soldering experience.
Do not modify any other part of the Triad circuit. Any other modifications
will void your warranty.