Hi there, first post to share what I had fun doing these last days : I'm the owner of a SR-3 and a SR-404 Signature, both powered by a 580V modded SRD-6 box. I'm very happy with the second hand SR-3 (especially for its low price) but I'm not exactly in love with the acid and harsh sounding 404, especially when listening to heavy/metal bands with loud guitars filling the whole medium/treble spectrum (Strapping Young Lad someone?) I recently read interesting stuff about the ED-1 and ED-5 equalizers, and I decided to try to emulate their behaviour with foobar and its convolution plugin. I eventually managed to find the schematics (thx to Mr. Gilmore, and to the filetype pdf search!) and first entered them in Switchercad III to observe their behaviour : Then I used RePhase, a complex but terrific program, and a lot of patience to generate my impulses : As you can see I decided to let the filters affect the phase like the hardware version does, but the EQs can be set on "linear phase" to avoid that behaviour. Another method would be to feed ScadIII with a 0.02s dirac pulse on the input of the circuit and to save the output as a wavefile, but you lose the flexibility and phase control allowed by rephase. I was eventually able to test them with the foobar's convolution plugin. Here are the links to the .wav impulses : http://www.petit-fichier.fr/2013/09/02/stax-ed-5/ http://www.petit-fichier.fr/2013/09/02/stax-ed-1-monitor/ http://www.petit-fichier.fr/2013/09/02/stax-ed-1-signature-1/ The custom curve is the one I'm currently tweaking to get the maximum out of my SR-404. Here you can see the green original ED-1 vs the red custom curve : Custom SR-404 curve (EQ + Diffuse Field) : http://www.petit-fichier.fr/2013/09/02/stax-sr-404-df/ Well, that's all. I hope you guys will find that useful and you'll give me some feedback and comments. Also, I'm desperately looking for the schematic of the ED-1 Signature model... Edit : All 3 Stax boxes + SR-404 custom correction.