Quoting david <gnome(a)hawaii.rr.com>om>:
1. Start JACK.
2. Start QSynth.
3. Connect QSynth to System output.
4. Connect my MIDI player to Qsynth.
5. Play MIDI - it works fine.
He does the same thing, and gets no sound whatsoever. But if he tells
QSynth to use ALSA or OSS, it works fine ...
I assume he's got a patch loaded in QSynth and volumes are well ajusted.
In that case it sounds like he's either missing out in step 3 or 4, as
in "MIDI info from the keyboard is not sent to QSynth" or "Output from
QSynth is not sent to the soundcard". The easiest way to check is to
use QJackCtl and check the Connect button.
It could also be that he's using the wrong Jack MIDI driver, check
QJackCtl's Setup button and test different MIDI Drivers.