Hi folks, I was recently stuck on an issue that I could not readily find solutions for online. So I thought documenting the solution here may be of use to someone in the future. Problem: when attempting to start two independent instances of fluidsynth in server mode from the command line, I get the following error: fluidsynth: error: Failed to bind server socket After a bit of research, it seems that the problem is a result of the fact that in server mode (and probably in other modes as well, though I am not sure) fluidsynth communicates with the shell through a socket on the local machine. From what I saw in the source, there is no automatic checking to see if the default port is already bound, so the second instances tries to grab the same socket as the first, and fails with the above error. There is a setting "shell.port", which needs to be set explicity in this case (see man page). the -o command line option allows one to define settings. In the end, the following two commands give me the kind of environment I need (notice the "-o shell.port="): $ fluidsynth -a jack -m alsa_seq --portname=fluidsynth_piano --no-shell -s -g 1 \ -o audio.jack.id=fl_piano -o shell.port=9800 piano.sf2 & $ fluidsynth -a jack -m alsa_seq --portname=fluidsynth_drums --no-shell -s -g 1 \ -o audio.jack.id=fl_drums -o shell.port=9801 drums1_harris.sf2 & I do not know if this problem occurs when using Qsynth, I am doing this in a text only environment. Machine info: $ uname -a Linux mervag 3.12.1-1-ARCH #1 SMP PREEMPT Thu Nov 21 08:18:42 CET 2013 x86_64 GNU/Linux $ jackd -V jackdmp 1.9.9.5