How do I get sound output from a MIDI keyboard?

I'm running Arch, and I want to run my AKAI MPK mini mk II through Qsynth. I have gotten to the point where, when I press a key on the keyboard, Qsynth acknowledges it, however it makes no sound. Qsynth does have a soundfont installed (I've tried several, currently FluidR3_GM.sf2), and from qjackctl I can see that the keyboard is connected to the FLUID synth's input, and qsynth's outputs are connected to the system inputs. But no sound. Edit as of 08-Mar-2022: It just works now. A couple of days ago, I decided to try again. I opened Qsynth, tried to connect the keyboard to it, was told it was already connected, and then I pressed a key and it made sound. I have no idea what changed; perhaps something updated, and that's all.