Audio Diff Maker Help! Options

[Tenson]

Hi all, I'm new here.

I wanted to find how much my pre-amp added to the signal, so I thought I would try to record with my M-Audio Fast Track Ultra output linked directly to the input, and then do the same with the pre-amp in the chain and subtract one from the other, leaving only the difference the pre-amp adds. I was using Adobe Audition to do that and it never nulled better than -55dB.

I then found Audio DiffMaker so gave that a go. http://www.libinst.com/Audio%20DiffMaker.htm

To test if it is working correctly I took two recordings, one directly after the other, of the soundcard output linked to input and tried to subtract them with DiffMaker. No matter what settings I use, I can't get it to null better than -78dB!

Is this normal? It seems very wrong but I can't find the problem, the soundcard seems to be working right.

I uploaded the two files:
http://www.audiosmile.com/forum/soundfiles/Direct.wav
http://www.audiosmile.com/forum/soundfiles/Direct%202.wav



Thanks!
Simon

This post has been edited by Tenson: Dec 28 2012, 01:51