From the Two-Rock website:
The Two-Rock Effects Loop Interface is an effective tool when using outboard effects with any guitar amp that has a passive effects loop with a preamp output, and power amp input jack. The buffered interface eliminates the insertion signal loss of effects chains by eliminating impedance mismatches created by various outboard effects units. In addition, compensation for hi frequency signal loss resulting from multiple effects being daisy-chained as well as long cable runs can be implemented.
