A .cue file is a text file that stores information about the data in a binary file, the .bin file, making up the so called cue/bin pair, the .cue file must point to the corresponding .bin file and can contain information about the individual track or tracks encoded in the .bin file, in the case of a Compact disc image, the audio can be encoded as tracks in the .bin file, the .cue files contains cueing (INDEX numbers) information along with CD-Text information of individual tracks, .cue files can even be paired with .wav files the so called cue/wav pair it is made popular by a company called Goldenhawk that made the CDrwin writing software, this format along with .nrg and those from various cloning software are the ones to encode audio cd to, .iso can not be used for audio cd imaging unless you have a special mounting software that can read .cue/iso where the .wav files are stored in the .iso, not all CD emulation software will read the .cue/iso, Daemon Tools on Windows will.
If you want to do as dv3500ea suggests, use the banshee media player to rip the cd to .flac format, if you then for any reason need an audio cd image from the ripped tracks or any other tracks in your library, banshee working with brasero can be used to create a cue/bin pair, you do this by selecting the tracks in banshee, right click on the selected tracks and click the WriteCD menu item, brasero will be called up with your tracks ready for writing, you then select the image option, just make sure the image is created in the cue/bin pair format.
after saving and brasero finishes you can use a text editor to open the .cue file and make the path pointing to the .bin file relative instead of absolute,this makes the pair more portable, you must make sure the .cue and the .bin files are in the same folder.