Available as an assembled Module and as a DIY project.
This Module is currently available.
Quad balanced outputs and two passive multiples
The Oakley Router is a simple but useful module. The top section offers two passive multiples. The bottom section contains four identical inverting amplifier circuits. The amplification is set when building the unit. Useful gains are either -1 (modular synthesizer output level), -0.33 (audio line level), or -0.1 (suitable for effect pedals). Each output is balanced and uses a 1/4” TRS (tip ring sleeve) socket which can be connected directly, using a balanced cable, to a balanced input of an audio interface or mixing desk without introducing ground loops. The outputs can, however, also be used with unbalanced inputs, and the outputs will not be damaged if you use standard mono unbalanced (TS) cables.
Each of the output amplifiers are inverting, that is a positive going signal is turned into a negative going signal. This has no audible effect on the audio signal but will change the polarity of any control voltages passed through it. The module could thus be used as an effective quad inverter if required.
These merchants probably sell this module. Huh?