Is it possible to enter or edit external MIDI instrument definitions in Samplitude? When I set a track's output to MIDI out, the program lists only GM instruments. This does not allow me to easily set programs for my non-GM external MIDI instruments.
I haven't seen the Samplitude Music Studio 14 yet, where did you find it? I assume it is similar to Music Studio 12. If you have selected the track to be MIDI and you have set the input to the keyboard, you should have the ability to select the output to be that of the device you wish to use. That would be the "program change" and within the output setting you would find what you system and device can provide.
To provide the instrument sounds, you can use : - either VSTi - or external MIDI instrument
If you want to use VSTi (Vita, Revolta, Sampletank etc.) you will have to declare the right VSTi instrument in the MIDI OUT of the track
If you use external MIDI instruments, you will have to select the corresponding MIDI port in MIDI OUT. Then the available instruments of your external MIDI synth will be used and the mapping is done using the MIDI channels