When you use test tones either from your receiver or from a test disc you should calibrate them to the same level as all the other speakers using your Radioshack SPL meter. Then you'll be good to go!
Using an SPL meter and sitting at your listening position, you should set all of your speakers to the exact same output level. If you don't have an SPL meter you'll have to do it by ear, but they all should be the same volume.