[header] How to play your ipod or mp3 through an amp [title] Discern the type of amp you have. [step] Most modern amps have standard rca audio inputs (similar to the red and white inputs on a television) on the back. Both these and the output on your ipod or mp3 player are 3.5 millimeters, so they'll work with standard auxiliary cables. 
[substeps] Some old models of amps have 6.35 millimeter inputs, which match 1/4 inch headphone adaptors. These won't accept standard 3.5 millimeter auxiliary cables.