[Festivuss]

I own one of the Grace Design m9XX DAC/Amps and have been trying to figure out the effective difference between the four DAC Filter settings (F1 - F4).
 
Research I've done thus far has been somewhat vague as to the results.  Has anyone tried out the filters thoroughly to see what affect they have?  I realize the desired result will be subjective, but I'm pairing up a set of HD-700's with this DAC/Amp and trying to see if I can cut down on the harshness in the treble a bit.  It seems that the F2 setting works the best for me, but I'm not sure if that's just 'in my head'.
 
Just curious about what others are setting their m9XX DAC Filter setting on for their particular set of headphones.
 
I've been reading the forums here for years to learn and finally jumped into getting some decent headphones and amp a couple months ago so I figured it was about time to be a participant in this active community.

 

[fjrabon]

the filters don't impact the frequency response at all, at least in a direct way.  They simply adjust the the impulse response in the time domain, and are mostly for dealing with various types of distortion that can pop up in highly compressed modern pop music and when using an external tube amp.  That being said, they can theoretically impact some headphones that have weird phase issues causing shrillness.  I believe the HD700 does have some phase problems that cause its shrill treble and peakiness, and F2 would potentially help tame that a tiny amount, as it will help alleviate the HD700's treble response overshoot.  F3 could also potentially help.

 

[Festivuss]

That makes sense, it's that shrillness I'm looking to tame and it does seem to help just a bit on F2.  Seems like if I avoid F1, which tends to enhance that peak in treble, I'm better off.  Thanks for your response, fjrabon.