system testing discs?????

Most of the Chesky discs' tests are conducted using your ears as the only "equipment." Some also contain test signals that are recorded at very high levels, and require an oscilloscope or wave analyzer to be of any actual use. Turn your volume down before playing any of those. There are also some tracks that are recorded with dither added. Here is a bit of info about the subject: (http://www.ethanwiner.com/dither.html) Probably the most useful for analyzing your room and set-up will prove to be the LEDR test on Vol I. Have fun!!

I suppose I should have addressed the question of an SPL meter with regards to the discs. I guess you could use one to analyze you system's lower end response with disc CHE 151's sweep tone(from lower mid to 20 Hz), but keep in mind how terribly inaccurate the mics are in most SPL meters. Even the Behringer ECM 8000(commonly used with the DEQ 2496) rolls off drastically below 100 Hz. Unless you have a Real Time Analyzer that allows you to enter calibration data supplied with a specific mic(ie: LinearX or TacT mics), and makes corrections for that curve in your readout: You won't have an accurate picture of what is happening in your listening environment. Might as well stick with your ears as your test equipment.