The Harvestman Stilton Adapter

via this auction

"4-Channel floor effects adaptor and instrument amplifier.

The Stilton Adaptor provides level matching for convenient attachment of instrument-level effects devices into a modular signal path. Each channel features up to 30x gain (noninverting), wet/dry crossfade, and a compact two-way TRS connector.

This module requires 1/4" TRS insert cables for bidirectional transmission using effects devices. Instruments and their effects chains can simply be connected with a TS cable.

There are 4 channels of input/output to enable you to use your favourite stomp boxes with your modular synth or process instrument level signals cleanly."