The VN-1100PC is designed for voice recording. The internal mic and preamp is too sensitive to record loud music. The result will be lots of distortion and clipping.
There's no option for external mic, but I believe you might be able to record a line input from an external preamp and microphone(s) better suited to loud sounds.
The recorder uses CELP and ADPCM file format, two compression techniques designed for voice recording. They're not popular for music recording. Olympus probably has some software to help play these formats back on your PC. I think you'll have trouble playing back your recordings on other devices.
All these issues mean you are unlikely to get good results when recording music with the VN-1100PC. It's a good machine for dictation, so you might be able to sell it and buy some recorder that would work better for music.
Flintstone