Signal corrupted using peak (biquad) filter at low frequencies I'm trying to process an audio stream through a series of peak filters at static frequencies that range from 0 to nyquist. If I start the range from anything below about 25Hz, the audio gets corrupted in some way (I haven't looked at the values yet, so I don't know what the corruption looks like) that results in no sound. But making the range ~25Hz to nyquist is fine. This happens even when all the filters are at zero gain. 

Is anyone aware of theoretical problems with using a low frequency peak filter? Maybe it's a problem when its bandwidth might cross over 0Hz? (Do standard biquad equations address that possibility?)
Looks a like a typical stability problem with the poles too close to the unit circle. A third octave wide parametric EQ filter at 25Hz sampled at 44.1kHz has a pole radius of > 0.999 so it's getting VERY close to the unit circle. The lower the frequency, the large the pole radius.The pole section alone has a peak gain for more than 110 dB !!!

With the poles so close to being unstable, you may run into all sorts of problem: numerical noise, noise amplification, coefficient rounding or truncation errors, filter topology (do NOT use Direct Form II or transposed Form I), etc.