I have just tried it, though my use case is different to yours (DOSBOX ECE R4191 -> Windows 10 -> USBtoMidi -> CM-64).
Using "S101 MT32" to start it got me music and I got into the game with no issue. I can try my MT-32(old) tomorrow if it's useful to you. I ran the GOG version of the game which has the following size/files for 101:
6,080 BELCH1.RS
9,984 BIP1.RS
25,024 BIRDS1.RS
6,800 CASTBAD2.RS
10,240 CASTGD1.RS
27,818 CHAPTER1.RS
33,232 CROWD4.RS
25,319 DOOR1.RS
8,653 HEART2.RS
12,864 HORSE2.RS
14,208 MONSTER1.RS
6,656 MONSTER4.RS
213,488 MUSIC.RS
1,712 RAT3.RS
776 READ.ME
13,463 RESTART.DAT
23,424 ROTTEN3.RS
4,060 S101.BNK
71,906 S101.EXE
327,904 S101MAIN.EXE
247,328 S101MAIN.OVL
106,273 S101STR.DAT
83,879 S101_C1.PIC
81,465 S101_C2.PIC
83,789 S101_C3.PIC
88,667 S101_C4.PIC
76,898 S101_C5.PIC
86,554 S101_C6.PIC
225,893 S101_E1.PIC
207,880 S101_E2.PIC
229,169 S101_E3.PIC
245,584 S101_E4.PIC
223,547 S101_E5.PIC
234,178 S101_E6.PIC
36,614 S101_M1.MUS
62,479 S101_M2.MUS
43,810 S101_M3.MUS
16,710 S101_M4.MUS
20,321 S101_M5.MUS
24,903 S101_M6.MUS
954 S101_R1.RGN
1,566 S101_R2.RGN
1,296 S101_R3.RGN
1,362 S101_R4.RGN
960 S101_R5.RGN
1,338 S101_R6.RGN
7,123 SB-SOUND.COM
3,653 SCREAM1.RS
16,986 SCREAM2.RS
16,986 SEX1.RS
13,631 SEX2.RS
8,653 SEX3.RS
16,986 SIGH1.RS
5,760 STAMP2.RS
25,415 VOCAB.DAT
28,480 VULTURE2.RS
56 File(s) 3,420,701 bytes