There are 64 filters total within the I-Tech DSP and they can be placed anywhere within the system. In addition to filtering,each possesses up to +/-24dB of gain . 

The following filters are available: 
Lowpass::Bessel 2-4,Butterworth1-4,and Linkwitz-Riley 4 
Highpass:Bessel 2-4,Butterworth1-4,and Linkwitz-Riley 4 
Lowshelf::Low-frequency shelving EQ 
Highshelf:High-frequency shelving EQ 
Lowpass EQ:Variable Q from 0.1 to 35 
Highpass EQ:Variable Q from 0.1 to 35 
Parametric EQ:Variable Q from 0.1 to 35 
All Pass:1st and 2nd order 

All Pass filters provide no gain change to the output , but provide a phase change at the selected frequency. This corrects the phase relationship of the output without a gain reduction, such as is found in other filters.