nwfiir and its accompanying software wfird allow design and use of a HiFi quality digital equalizer based on a WFIR filter (Warped Finite Impulse Response). It can take advantage of multiple processors, e.g. on a dual Pentium II 300 MHz it manages to run a two-channel equaliser with 275 taps, with 16 bit 44.1 kHz input, and 24 bit 44.1 or 88.2 kHz output. This is more than enough to very precisely equalize the whole audible range from 20 to 20000 Hz. The equalizer can be used as, and was designed for, a key component in a room equalization system. Non-realtime operation is also possible on slower machines.