You are more than likely hearing pre-echo in the filters. Time domain artifacts of ringing filters are much more perceptible (read: trigger human audio perception responses) than small scale, fairly linear component distortions, in my experience. Haven't seen jj (Jim Johnston) on the net for a few years, but he can tell you more than you care to know about the subject. [Maybe look up some articles or google away...] Phil Mendelsohn -- Dept. of Mathematics, 342 Machray Hall U. of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2 Office: 446 Machray Hall, 204-474-6470 http://www.rephil.org/ phil at rephil dot org