Hello Bill,

You are right, the second set of Midichannels are indead accessed by Sysex.

But i think to have the solution for my problem : a MidiMerger.

I need the Midi-Ext 1 Bank for the 128 GMvoices, to play the accompaniment.
(Accompaniment plays on 8 channels, channel 9 to 16)
I need the Midi-Ext 2 bank to acces 128 other voices from the SD2 to play on the manuals.(Manuals plays on 8 channels, channel 1 to 8)

I can merge Midi Out 1 together with Midi Out 2, to one Midi Out, with a MidiMerger Box.

But, with a Polyphonie of only 48 voices, it is perhaps, like mentioned by Bernie, better to buy a second SD2.

Greetings from Belgium.

Carlo.