I'd get the BeatStep Pro (BSP hereafter). It can control all of the DFAM, the Minitaur and the Sub 37 from its three sequencer tracks and its sync facilities.
The DFAM could be controlled either by using the BSP sync output or one of the drum trigger outputs connected to CLOCK/ADV to drive the sequencer, or by connecting gate and CV outputs to DFAM trigger and e.g. VCO 1/2 CV or VCF mod to play it directly without the limitations of the built in sequencer (no reset, always 8 steps). Alternatively, the DFAM could be the clock source, connecting its TRIGGER output to the BSP clock input.
The Minitaur could be hooked up to the BSP by MIDI and so can the Sub 37. The Sub 37 has it's own sequencer of course, which could be synced to the BSP either by MIDI or by using the BSP sync out connected to the Sub 37 KB GATE input. If syncing the BSP and the Sub 37 by MIDI, either of them can be the sync master or slave.
There are many ways you could hook up and use such a setup - it would be a quite powerful little rig
