MIDI data is send to the wavetable and the ext. MIDI port. So it will work fine, but if you actually have a wavetable connected as well, you need to mute it when using the SC-55, otherwise both will play. Some soundcards also allow selecting whether an internal or external MIDI device is used.

As far as I can recall, the original Waverider 32+ (I38-MMSN826) required a tsr in order to initialise the onboard wavetable chip (later versions were directly mapped to the MPU-401 MIDI interface), I'm not sure if these could be disabled within the software based mixer or via a jumper on the sound card itself. I have a scanned copy of the Waverider 32+ (I38-MMSN826) and nothing indicates that it can be disabled.
If you have the earlier version, simply not loading the tsr might enable you to play back the MIDI data via the external MIDI/game port.

Unfortunately, my I38-MMSN826 is non functional. Otherwise, I would have tested this myself.

Thanks for the help.
I have two cards on AZT2320 PNP - Sound Galaxy Waverider Pro 32-3D PnP I38-MMSN853 and Aztech Waverider Platinum-3D PnP I38-MMSN853 - sadly there is no dos mixer aviaible to change midi device and cards works without any configuration (ICU or tsr).
Another card (best one - bought new in 1995 😀 ) on AZT2316 non PNP - Sound Galaxy Waverider Pro 32-3D I38-MMSN847 - I need to see options in the software to mute the midi or select external MIDI device.

I also have yamaha ymf-715 and OPTi 82C929 (MAD 16) cards but I would prefer aztech cards for sentimental reasons.

I'm also a big Aztech Labs fan. Send me some pics of the I38-MMSN847, if you have a chance.
Creative Labs AWE based sound cards has the option to route the MIDI data to the internal synthesizer or the external MIDI port via the "SET MIDI=SYNTH:x" environment variable (where x = 1 for internal or 2 for external).