1. Download Roland SCC1 Utilities Disk from vogons drivers.
2. Place scmode.exe in the same folder as SF2TURBO.EXE, or in the MS-DOS path.
3. Run scmode.exe gs before starting the game.

Here is the way I have it set to run in my dosbox.conf as an example:

1scmode.exe gs
2SSF2T MIDI

Thanks! I'll give it a shot.
...
Well, when I run that, it tells me the it cannot find the midi interface.
Is that tool only meant for Roland hardware?

The only way I could get the message about not finding the midi interface is disabling mpu401 in dosbox. The Serdashop website mentions the following at DreamBlaster X2 - Serdashop, which may be applicable to you.

Please note: There are some older soundcards with a Waveblaster compatible header but don‘t have an MPU401 interface. Instead there is only the SoundBlaster MIDI standard supported so the games that run with the X2 module are limited. Also you need SoftMPU to emulate the MPU401 interface in this case. Visit http://bjt42.github.io/softmpu/ for further information and a list of compatible games.

Hmm, I will see if I can try and find some documentation about the header on this card, but I can say that it plays every other game I've tried, without issue, such as Doom and Duke 3D, and without needing softmpu.
Now that's got me thinking, SSF2T is set to MPU-401 in its settings, as it doesn't have a General Midi option.
From what I've read about my card, it has 'UART MPU-401'.
I think I'm going to try softmpu for this game, to see what happens. --> I tried it with the /OUTPUT:SBMIDI option, and got exactly the same issue with the wrong sounds.

You can also try GMGSMT32 in the youtube description that Vogons user Retro Erik posted DreamBlaster X2: The Rise of General Midi, to initialize the DreamBlaster X2 to GM/GS before starting the the game.

I've been playing more, and it's very strange, most of the time the music will be fine, then one round will start and the drums are wrong, and then it'll go back to normal the following fight. So it seems it's quite random. Weird.

May it requite to reset after each game?

Just a bit more clarification:
In the music test, under options, I can go through the different tracks, and usually they play ok, then a track will just play back with wrong percussion instruments, then try a different track and it will play ok, go back to the one that was wrong previously, and now it play correctly, or sometimes not... etc.
It seems like there is just a random chance the percussion instruments are wrong for any track, so doesn't seem to be about setting the gm state before starting, as it varies in game.
This made me suspect it might be a processor speed issue, and I'm now experimenting there, but so far it still seems to go wrong even clocking to 200 mhz and disabling L2 cache...perhaps I need to go hard and try disabling L1 cache as well.

I really like this soundcard/dreamblaster combo, so if I can't solve why SSF2T behaves like this, then I'll just have to live with it, and try to enjoy the funky 'remixes'.
If I do fix this, I bet i'll find myself missing the remix of E. Honda's stage featuring explosions instead of wood block hits.

This title looks to have been released in ~1995. My guess is that it would have been broadly targeted at higher end 486 systems or low end Pentium (P90 up to possibly P133 - though the latter was only released in 1995) - 200MHz is probably still way too fast. Try lowering the speed as much as possible - timing issues can play havoc with MIDI messaging.