In the PM-7 each preamplifier is independently configurable via a series of DIP switches that control gain and resistance. An additional DIP switch acts as a "rumble filter" to allow you to limit low-frequency response to 2Hz or 20Hz. Three DIP switches allow loading to be adjusted from 24 ohms to 1k ohm for moving-coil (MC) cartridges; and, for moving-magnet (MM) types, 47k ohms in unbalanced mode. There are switch positions for values of 24,130,150, 1k, and 47k ohms.
Capacitance adjustment for M Ms is limited: 100 pF. A Three-switch DIP-switch array offers gains of 80, 150, 775, 850, 1300, 1400, 1900, 2000 times.
The heart of the PM-7 is a super-quiet analog device microphone preamp based on op-amps. After the adjustable linear gain stage, the signal passes through a passive low-pass RIAA filter and the low-frequency cutoff switch, followed by active RIAA equalization. The low-impedance unbalanced signal can then be output directly.