On a possibly related note. I was hoping to use a 18Hz high Q cut as a "poor mans" subsonic filter. Running pink noise through 2b11. comparing the input (reference) and output using various PC&soundcard 2 channel analizers (SpectroLAB, SmaartLive, & EFT). I noticed that below around 40Hz the EQ stoped working, meaning the output trace just floated back up to match the refence level (averaging on) as I selected a center frequency below that point. It was in the High 30's I think. Can't post results, didn't save em sorry. I say "around 40" only because I don't remember, but there was a consistant frequency below which this behavior occured, and was consistantly reproducable in both 2 and four channel, independant and locked modes. I was using only the first band of the parametric, all others were flat.

This led me to think the only way to get a subsonic High Pass filter would to use an fmod (they come in 20Hz and 50Hz, -12db/octave) into the amp. An unfortunante solution because my starting parameters (which I'd hoped to tweak) were more like -24dB @ 25 Hz.

This was my first pass of playing with the Rio "on the bench" (PC). Then am now embarked on my install (dash, subs, amp, cap, etc.). I plan to retry this again and in the car when thats complete. And will reproduce and post more detailed results.

Michael