PV44 lets you select between 4 groups of 4 voltages via prioritized trigger inputs. 1V, 2V, or 4V range for the upper rows, +5V and ±5V for the lower rows. Common modulation input with an attenuverter per row. The 4 trigger signals also go to an OR logic gate, which proves to be handy when using PV44 with percussion synthesizers or envelope generators.
PV44 IMI adds a couple modulation possibilities to a stock PV44. The original PV44 modulation input is still effective when used, and becomes the modulation group I when a signal is inserted in the bottom jack on the expansion (group II). The groups destination can be selected with a switch, and reduces the need of multiples. The top A/B/C/D jacks, directly go to their respective attenuverters. PV44 IMI comes with a 1HP blank.