First off, TG300B mode is not GM mode. It is GS mode.
XG modules do not have a GM mode. When a GM reset is recieved they enter XG mode. The XG System On sysex allows XG specific features to work. A GM Reset will use the XG mode samples and sounds. Your MU100 is XG level 2. The DB60 is XG level 1, so yes they will sound quite different as the 100 has a brand new set of samples for XG/GM. XG at its core is an extension of GM. GS was meant to be unique, and added GM support due to demand. TG300B on a 100 uses different samples then an actual TG300. And the TG300 samples are Yamaha samples, of course they will sound different then a 55's Roland samples.

To test your DB you should use actual GS midis.

Actually a very easy test would be to download a doom e1m1 midi file. Then edit it. The midis on say, doom world do not even contain a reset message. Edit the midi with a GM reset, then edit another with a GS Reset. Play these on your DB and you will hear the difference. Especially if play them both on your mu100 too

I see, this is much better and clear info than the manual.
Now, what is the right process to send the SySex message for the XG and GS reset using XGEdit or Midi-OX in Windows 98? Do I click the XG and GM buttons and then close the programs (If I leave them open I get an error that the MIDI port is busy)
Maybe this cannot be done in Windows 98 and only works in DOS?
I read somewhere that a cold Boot is needed to resent the DB properly...

BTW I am using only a computer, I have no external synth device like a Mt-120 or Mt-200

I would just make a MIDI file with the sysex you want then play it in windows media player...

Thanks, though what I am really trying to do is to work my way through how to reset the XG385 for games (doom, descent...). I want to know what steps to follow to reset the DB and play the games in XG and GS mode.
Not that interested in just reseting it to listening to off game single midi tracks.

As a work around I connected the sc-55 and Mu-100 to the sound card’s external Midi/Joytick port through a midi-Joystick splitter cable ... but this means I am not really using the DB but the sound modules.

Still looking for the right steps to follow to reset the card (cold boot needed, not needed,...)

Cold boot is definitely NOT needed. The effect of GM/GS/XG SysEx reset messages are not permanent, so if you reboot the system then your Daughter Board resets itself to its default state.
The problem is that e.g. DOOM is known to send GM ON SysEx reset so DOOM will overwrite the custom XG/GS
Midi system state you set by Midi-OX/XGedit to GM.
To prevent this you need to route the game's Midi out to an application (e.g my Midiplayer) that can filter out the reset SysEx messages sent by games but this requires software Midi cables that do not work reliably with DOS programs under Win98. But you can try nevertheless:
Windows port from DOS games

But instead of desperately trying to set your DB to XG mode first you should make sure that it actually makes any difference. The DOS games you mentioned do not use any advanced XG features and as SuperDeadite said the instruments are the same in GM mode as in XG. I suggest to download my Midiplayer (that was referenced also in the above link) since with it you can send GM/GS/XG SysEx messages in real time so you can hear the differences between GM/GS/XG mode while listening to e.g. e1m1.mid. To change the Midi system you can right click the first aid like Reset button on the right hand side of the player and select GM/GS/XG. The selected SysEx message is automatically sent by the player when a song is loaded but you can also send it manually by pressing the Reset button.

http://falcosoft.hu/softwares.html#midiplayer

A MIDI file containing no music data, just a reset sysex and played via mediaplayer works fine for mode setting. But yes Doom will reset your DB by itself. This is a bit overkill imo, but the Korg NS5R can use this DB, and it has a sysex filter option built in , you can tell it to ignore any combonation of GM/GS/XG reset messages. But, Id just stick to your MU100 personally. Does the Mu100 have "Mu Basic" mode? Basic mode will use old XG level 1 samples instead of the new set.

Falcosoft wrote:

Cold boot is definitely NOT needed

Thanks for clarifying that no reset was needed.

Falcosoft wrote:

To prevent this you need to route the game's Midi out to an application (e.g my Midiplayer) that can filter out the reset SysEx messages sent by games but this requires software Midi cables that do not work reliably with DOS programs under Win98. But you can try nevertheless

The FSMP MIDIPLAYER is greater than great. The fact that, as you indicated it, you can change from GM>GS>XG modes on the fly makes it very useful. Not sure if this is something common among other Midiplayers but this is the first that I come across in Win98 that does it and that it works.
I can both play the Doom midis as single files and switch the GM>GS>XG modes as it plays (after pressing the 1st aid + reset) or I can simply play the DOS Game (Doom) in whatever mode I select.
I notice though that if I play a DOOM Midi single files in GM and GS modes the Midi plays good both through the XR385 DB and through the MU100 module, however if I reset the unit in XG mode the instruments sound wrong, ...rather badly messed up in fact. This does not happen however in-Game with Descent, RAPTOR, Warcraft2 or even DOOM midi files, they sound good and sound different (not VERY different) in any of the 3 modes modes.

SuperDeadite wrote:

But, Id just stick to your MU100 personally. Does the Mu100 have "Mu Basic" mode? Basic mode will use old XG level 1 samples instead of the new set

Thanks!. The only Modes I see are available are XG > TG300 > C/M > PFM. I do not se a Basic mode listed. I will check on the manual but at least I do not see anything to switch between XG2 and XG1 on the screen menu

I notice though that if I play a DOOM Midi single files in GM and GS modes the Midi plays good both through the XR385 DB and through the MU100 module, however if I reset the unit in XG mode the instruments sound wrong, .

Since DOOM midi files use only capital tones that theoretically are the same in GM and XG modes the only thing that can cause weird sound are not melodic instruments but drums. It's because some XG implementations do not treat channel 10 automatically as a Drum channel (unlike GM where channel 10 is the dedicated and only Drum channel) but require Bank MSB set to 127 on channels to treat them as a Drum channel. So you can try to select manually Channel 10 on Midiplayer's interface and set Bank MSB to 127, or you can make this automatic by opening 'Main menu-> Compatibility Settings' and check 'Fix Sfz Drum Bug (Force XG Drums)'

Falcosoft wrote:

So you can try to select manually Channel 10 on Midiplayer's interface and set Bank MSB to 127, or you can make this automatic by opening 'Main menu-> Compatibility Settings' and check 'Fix Sfz Drum Bug (Force XG Drums)'

Thank you!, That fixed it. you are gold!.
FSMP is awesome, I am going to stick to it as my default tool.

SuperDeadite wrote:

But, Id just stick to your MU100 personally. Does the Mu100 have "Mu Basic" mode? Basic mode will use old XG level 1 samples instead of the new set.

Confirmed. It has 'MU BASIC' mode menu but as far as I can tell, either in 'Native' mode or 'Basic' mode it shows the same issue with the drums channel 10 (in XG mode), That is unless I force the Bank 127 fix in FSMP.