samples/recordings from analog in have loud snapping sounds

[Beenwiser]

When I play back stuff I captured from the audio input, there are loud digital snapping sounds all over it.

I'm set to mono analog in, using one side and keeping the input volume on the other side at zero.

I don't think I'm clipping - I recorded a period of total silence as an experiment and the noises are still there.

I don't have the clip for the phono jacks, so I took jumped all 4 pos & neg leads together on a couple RCA jacks and plugged that in to see if it resolves. That made a humming noise so loud I had to immediately remove.

I'm not hearing the snaps in the headphones when I'm setting up and recording, just on playback.

Also listened to a bunch of samples from previous owner(s) and heard this same noise on most of them

i haven't initialized, machine appears to have OS 3.01

[Beenwiser]

sorry I'm a newb dummy, afraid to initialize because I don't know if my first song I started will still be there after