It is about the source and destination devices.
I tried to load them sometimes, but I never found out, what their purpose whas (yes I know RTFM). Now I know

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I have made 3 new subfolders in my "tools" folder and filled them with renamed source and destination devices:
1) inputs (here I have my hardware inputs)
Mic (ADAT

Dat (SPDIF)
Tape (analog in)
Guitar (ADAT 12)
2) record (here I have my asio destinations),
Asio 1L
Asio 2
Asio 3
Asio 4
Asio 5
3) playback (here I get sound out of Samplitude)
Rythm guitar 1 (asio 1l)
Rythm guitar 2 (asio 1r)
Rythm guitar 3 (asio 2l)
Bas (asio 2r)
Solo guitar 1 (asio 3l)
Solo guitar 2 (asio 3r)
Percussion 1 (asio 4l)
Percussion 2 (asio 4r)
Percussion 3 (asio 5l)
Percussion 4 (asio 5r)
Synth 1 (asio 6 l+r)
Synth 2 (asio 7 l+r)
Synth 3 (asio 8 l+r)
Voice 1 (asio 9l)
Voice 2 (asio 9r)
Klick/mix (asio 10 l+r)
Choir 1 (asio 11l)
Choir 2 (asio 11r)
I have my ASIO source/dest loaded in a far corner in my projects (together with my hardware I/Os).
In Samplitude I have renamed my inputs and outputs, so they match my SFP source/dest devices.
Next may be to connect some old junk to my a16 and use the external effect devices.
I find this very convenient for reducing cable clutter in my projects. Unfortunately, I can not have more devices use the same inputs (as can be done with traditional routing). I just got to think: I didn't try loading 2 instances of the same device.
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Sorry, if I waisted your time. But SFP is still rather "big" to me, as I normally only use a very small portion of the options. Maybe someone else has it the same way.
Immanuel