Hi!

I've been trying to record the sound output with Audacity like I used to on my older machine. Usually, I would just set it to "stereo mix" or "volume" and it would record whatever the computer was playing at that moment.
Currently, this option doesn't even come up on audacity, and I realised that you have to set it as an "input source" on alsa. The problem is, while on other machines there is usually a mixer option of some sort, on mine the only three input sources that seem to be available are Line, Mic and Front Mic.
Sound works okay and microphone recording does too. I just can't do it to the output stream.
I have installed alsa-drivers for this chip. It's a Realtek ALC888 on a Geforce 8200 chipset board. It seems to use intel8x0 module.

In a terminal window, have you tried the command, 'alsamixer' to make changes or you can install the 'alsamixergui' for a GUI interface.

yes I have done that. All of the mixers I have used (including kmix, alsamixer, alsamixegui) have only showed this three options.