did you connect the audio out of the mt32 to your speakers (those big connectors are the sound out) ? (and volume control set correctly)

That was it, thanks - I was assuming it would come out through the speakers on my PC, but was wrong. Thanks!

That's a common mistake 😀
(and if you have several such devices a hassle)

Dominus wrote:

That's a common mistake 😀
(and if you have several such devices a hassle)

Fortunately my SC-88 has a line-in jack and MIDI passthru, so in my case I was able to daisy chain both the MIDI in and audio out lines of my SC-88 and MT-32. To use the SC-88, I turn off the MT-32 (it's on the end of the chain). To use the MT-32, I mute the SC-88 (it needs to be on for passthru to work)

The only thing I don't like about my setup is that the line-level input jacks on my Xonar DX are quieter than DOSBox + Windows 7 output by default, so I have to turn down DOSBox's internal mixer and turn my speakers up to compensate. The other option is to use my onboard Realtek chip's line-in in combination with Windows 7's "listen" feature to route it to my Xonar DX in software, but I don't do this because I'm paranoid that it will add extra latency.