I agree with Carl, get a known Calibration Disc. It's certainly easier and cheap to have. Your tests may be valid, but I'm not sure how you know what your reference is in digital domain to compare it with analog. Seems very problematic way of doing it, that you'll get your self in a pickle. It's tricky enough getting everything correct and well understood even with the calibration disc never mind without one.

You should get the Oppo hooked up digitally anyway smile

- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
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