OK, I'm a total beginner at all this dsp stuff, so forgive ... One way of subjectively "widening" a stereo image is to do the following: feed the left channel back to the right with a short delay, inverted; feed the right channel back to the left with a short delay, inverted; By inverted, I mean change the sign of each sample (assuming we have floating point samples). So now the newbie question: how do you invert the signal? I have the rest of the algorithm here: // note: sndbuf only seems to read in one channel of the source, so use one file for each channel of stereo source // sound file "r.wav" => string right; "l.wav" => string left; // the patch SndBuf l, r; DelayL dl, dr; l => dac.left; l => dl => dac.right; r => dac.right; r => dr => dac.left; .2::second => dl.max => dr.max; 15::ms => dl.delay => dr.delay; 0.4 => dl.gain => dr.gain; // load the file left => l.read; right => r.read; // time loop while( true ) { 1::second => now; } -- Rich