Supply the make and model for them to help. I use an audio recorder because I've found most MP3 players to be poor recorders. There are many models but I see the model over my shoulder so mine is the Sanyo ICR-XPS01M. It's very good.
I'm looking at a few models under $100 and the instructions and spec sheets don't say anything about whether they record in stereo or mono. I looked at a few voice recorders and some of them indicate that the built-in mic only records in mono, despite recording at 44.1 kHz and 192 kbps. I'd like to know what mp3 players can record in stereo. Is there a way to tell?