Available as an assembled Module and as a DIY project.
This Module is currently available.
TRS Utility
This 'TRS' module gives you four utility functions for TRS jack connections. They can all be used for stereo audio and some will function for MIDI TRS and mono signals or CVs.
Stereo attenuator Level control of a stereo signal. Can also be used for mono signals or control voltages.
Mono to Stereo converter Plug two mono signals into the mono jacks - these are combined into a stereo TRS format at the the Stereo jack. Also works the other way round taking a stereo signal and splitting it out to the mono jacks. If nothing is plugged into one of the mono jacks it is normalled to the other one, so a single mono signal will appear on both channels of the stereo signal.
Swap Switches the tip and ring connections, so can be used to switch the left and right channels of a stereo signal or convert MIDI 'A' format to MIDI 'B'
Switch Connects the I/O jack to the A or B jacks in stereo. There is also a centre mute position. It is bidirectional so can be used either way round. Can also be used for mono signal or MIDI TRS (Switching MIDI when notes are playing is not recommended!)