Update 6/5/2012:

Still trying to perfrct the "tune" using RTA tools. Getting closer but has a setback because my laptop sound driver would not register the SPL of frequencies above 5Khz.

In the initial settings menu there is a switch for "digital attenuator".


Correcting distorted sound
When listening to a CD or other source on
which the recording level is high, setting the
level of each frequency to high may result in
distortion. You can switch the digital attenua
tor to low to reduce distortion.
! Sound quality is better at the high setting
so this setting is usually used.
1 Use MULTI-CONTROL to select
Digital ATT in the initial setting menu.
Refer to Adjusting initial settings on page 35.
2 Press MULTI-CONTROL to select the digital
attenuator level.
Pressing MULTI-CONTROL repeatedly will
switch between High (high) and Low (low)
and that status will be displayed.

I wound up turning it to "low" yesterday becaues some of the vocals on a CD sounded a litle raspy / distorted.

It did sound better in the low position. More listening to come about this feature. I had first understood this to be an aid when playing digital media but not so.

Based on the burried menu layer it's difficult to do a quick A-B comparison but I do find the "low" position sounds noticeably cleaner.