At the program startup, a dialog may offer to play sound on some channels and systems until the user can hear a tone. If the user cannot hear the tone, Frinika can help them diagnose the problem.
This is important because there are lots of setup problems which cause sound not to work: permissions, selecting other device, wrong transport (alsa, oss, jackd, …), having volume too down, channel muted, wrong connections in jack, … And you want nevertheless to cause the user a good first impression.
Sounds like a good idea - so that dialog could then contain a list of audio devices, possibility to adjust latency, and maybe also for external MIDI devices. A picture that illustrates how you see this dialog would be great (attach file to this topic).