ran a quick test using a single filter (LS 80Hz +2dB Q=0.707) and then repeating that n times, was fine til I tried it with more than 6 biquads which resulted in a burst of 0dBFS high frequency content. Tweeter and ear melting stuff basically hence I think feature is currently unsafe to use til that bug fixed (I run these tests silently as I've nearly melted my ears more than once in my life doing this sort of thing!)
i.e. with this at 48kHz, it goes bad but remove biquad7 & biquad8 and it's ok (independent of internal volume)
biquad1,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad2,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad3,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad4,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad5,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad6,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad7,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682,
biquad8,
b0=1.0008534559678395,
b1=-1.9860043906796208,
b2=0.9852731227640296,
a1=1.9860169559958216,
a2=-0.9861140134156682