SSL did indeed work very closely with Universal Audio in the sonic, technical and functional evaluation of our existing emulations, and had specific requests for what features they wanted added to the newly licensed plugins. In the case of the SSL E Series Channel Strip, the desire was to add the "brown EQ" that came from the very earliest E Series consoles. It should be understood that this EQ is different on every band, LF, LMF. HMF and HF. Center frequencies, Gain, Q are all different; not just the LF bass band. Also, the LC filter is 12dB rather than the 18dB found on the black. Similarly, SSL requested the inclusion of the Auto Fade feature from the original G console in the SSL G Series Bus Compressor plug-in. SSL required changes for our "black EQ" model, which came down to calibrating the Q/Gain relationship closer to factory calibration standards on all bands (the console we originally measured had a custom calibration that differed from the factory cal).