Fons, If I insert the filter such way (via JACK, jack-rack): jaaa_out - card_out - cable - card_in - THE_FILTER - jaaa_in, how can I interpret the result in terms of SNR? Andrew ======= On Monday 14 March 2005 02:32, Fons Adriaensen wrote: ======= Hi LAD, If ever you need a high precision A-weighting filter (as used for sound level metering), you can find one in the usual place: <http://users.skynet.be/solaris/linuxaudio> The tarball contains a C++ class implementing the filter (easily converted to C if you want that), and both a JACK in-process client and a LADPSA plugin using it. -- FA