they are line level outputs, so unless you want to listen to really silent music or potentially risk a lot of clipping I would suggest so, yeah :p

I was thinking so too, ok thanks 😀

second question:

For setting up on my old PC i can use the midi port on my soundcard ok. But if i have the chance to get a MPU-401, should i go with the external or interal version?
What are the differents beside the one is isa and the other external. Do both exactly the same job ?

thanks 😀

All original Roland MPU-401 interfaces for the PC require an internal ISA card and external breakout box .

Later Roland MPU-401 models and MPU-401 clone cards may consist of in ISA card only .

There are no external only MPU-401 interfaces, they all require an internal card .

See https://en.m.wikipedia.org/wiki/MPU-401

EDIT : some corrections

you have 2 options to drive a MT-32 when the "roland intelligent mode" is needed

1. software option: SOFTMPU that will work with existing soundcard mpu
2. hardware options:
a. find an old roland or compatible interface
b. get a hardmpu or pcmidi card

got it thanks!
regards
Chris