ok
thanks for all replies. Ive tried it as well now and are working without any problems!
I use a Rode NT4 mic directly into the optical in & the recordings all turn out great
just for your own reference:
the optical in is a digital input. when u recorded u used the line in. its not possible to record digital through an analog mic. you need something that converts the analog signal into digital, an A/D converter.
/ p