Hi Felipe,
The Debian Multimedia Maintainers will be dropping libjack0.100.0-0 soon, so you should switch to using upstream's default name. Changing libjack0.100.0-0 to libjack0 in debian/control and dropping debian/patches/80_libjack.dpatch should be enough.
Unfortunately not in the longer term, there is a more serious bug that amsynth does not work with JACK 2 at all (for example, the current upstream 1.9.2 release of JACK).
I have contacted the upstream author of amsynth about this, but it seems the application would need a partial re-write, as the way it currently opens JACK ports is non-standard.
Cheers! Daniel -- To UNSUBSCRIBE, email to debian-multimedia-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org