I havde and use both here.

SD4 is merely TWO SD2's inside.

One of the two synths is programmed *exactly* like the SD2 and they share the same Patch set, can even run from the same Patchmap.

The other synth contains the Solo voices, 64 of which are hard written and the other 64 which are User assigable for making Custom patches such as those patches you may wish to combine two or more of the available voices as one patch. Like Piano and Strings at the same time.

While it is possible to address and use both SD4 synths inside RB and PT, with BiaB we can only assign one MIDI synth at a time, and that should be a GM compat synth, so you should be addressing only the voice that is controlled by the 'MIDIFILE' volume button on the SD4. This synth uses the exact same patch set and patchmap as the SD2. The are identical in operation.


--Mac