[hjb]

Hi, (Noob here)

OK, I'm not a headphones user

, but I have been following the DAC-AH threads here which are excellent and am now enjoying my own DAC-AH.

I use a technique called Digital Room Correction (again, would not be relevant to headphones) which creates a digital filter on the source PC to compensate for room acoustics. In short, this requires the playing of a sine wave from e.g. 20Hz to 20kHz and recording the amplitude and time responses - the software creates a filter which is convolved with the source material and corrects for poor room acoustics. All this happens on my source PC.

Since introducing the DAC-AH into the equation, I now have a strange effect - when the wave gets to about 12 - 14kHz, insted of continuing on it's rise, it sounds like it troughs down a few KHz then goes back up.

I am feeding the DAC-AH from an M-Audio transit - if I bypass the DAC-AH and take line-out from m-Audio to my Marantz 5200 (via analog is fine so is via SPDIF) - all is fine.

I am thinking that I have some harmonic effects going on - any ideas ???

Thanks!!

HJB