I am not very familiar with MIDI connections. Could somebody help me?

I have an MMX PC build where the MP32 unit resides inside the PC case. The MIDI cable comes out the back of the case and connects to the DB15 MIDI/joystick port. It is not an elegant solution, but so far it has worked just fine.

Now I have the situation where I need to use a joystick as well. So, I thought I could connect the MP32 internally to the soundcard. My first thought was to solder the MIDI cable to the soundcard's rear side (on the PCB DB15 connections). But then I thought it might be possible to modify the MIDI cable and connect it directly to the daughterboard connector. This way, I can easily disconnect the MIDI cable if needed, and the soundcard remains unmodified. My question is: is the MIDI in/out signal on the daughterboard connector the same as on the joystick port?
I already searched for pinouts, but that confused me. I see there some differences: on the DB15 port, I see MIDI in/out labels, while on the daughterboard connector, there is only MIDI TTL.