ISO files are not very common for music. If your ISOs are of Audio CDs they will be around 600MB. If they are SACD they will be closer to 4GB.
MC handles SACD ISOs directly without any configuration.
I've never seen an ISO of an audio CD. Disk Utility (included with every Mac) can probably mount the ISO. But once it's mounted, I'm not sure what you'd do with it. You would probably need to rip it using a CD ripping program.
Maybe look up some information on using ISOs on Macs. Figuring out what you have first would be a good idea. Then you at least know what you have.
Generally speaking, ISOs of all types are a poor format for audio or video. They are always weird and require special handling. FLAC for audio and MKV for video solve most of these issues and make ISOs unnecessary. ISOs are really only for people that have very particular desires (for example having entire DVDs including menus). Most people are better off with a different format.
Brian.