Very hard to tell, but most HDCDs don't seem any louder or softer than normal CD's to me. I think HDCD, personally, is a bunch of hooey. I've heard better results with good quality upsampling (44.1 kHz to 88.2 kHz) capable DAC's compared to HDCD's decoded on an HDCD capable player.
By the way, the Model 950 doesn't decode HDCD anyway. Could be just a change of signal levels between what the player is outputting via its analog outputs vs. what the Model 950 is doing internally.
Dan
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Down with the MPAA!! They are robbing you of your rights in the name of greed!