Two of these rack-mounted pre-amps were used in Billy's 2000 Machina-era touring rig.
The Matchless GPR is a 2-Channel Pre-Amp that contains their "Lightning" amp circuit on Channel 1 and their "Chieftain" amp circuit (but without reverb) on Channel 2. Around 1998 when these were first (and last) made, the Matchless company was going out of business (later to be reopened under new management in 2000). Legend has it that only 30 of these pre-amps were ever made.