Mini Disc To G5; Di To G5 Options

[mpnow]

Two related questions;

1) I have sketches of rough songs I recorded with the aid of a tiny little stereo microphone on a sony minidisc player. I would like to put them onto the hard drive of my G5. How do I do this?

2) I have been trying to start recording these sketches straight onto the mac (into Garageband) using exactly the same little microphone that I used to record onto the sony mini disc, but without any success. I do not understand why not.

I have checked that
(a) the mike still works by using it on the mini disk player again five minutes ago;
(b) in my 'system preferences' I have made sure that the 'input' is on 'audio line-in', that the volume control is up as high as it will go (though it seems to refuse to stay there and become the default volume setting);
© that the tiny little jack of the mike is plugged into the audio input jack on the back of the G5; and
(d) in Garageband, the new track is a 'real instrument' (voice).

Do not see what else I can do (I have not yet tried plugging the mike into the headphones socket on the front as I do not want to damage anything). Anyone any suggestions that will do the trick with the tools I have before me?

[mpnow]

just for the record, I just checked. MD has Optical line in, but no Optical line out. (On my Sony MD there are 2 lines out. One is marked Phones/Remote.)

The G5 appears to have a mic input. On the back of mine there are two stereo jack connections. One is for the line out (for speakers), and the other, I presume is for line in (it is marked by two black triangles pointing towards each other).

The systems prefs for 'sound' and for 'speech' both allow you to adjust the level of "audio line input", although in my case it keeps defaulting to the minimum.

As for those MBoxes, is it mainly size that makes them a better alternative to getting a small mixing desk?