Digital Filter Plus is now also compiled for Apple Mac OS X.
Digital Filter Plus can be downloaded from here : http://www.numerix-dsp.com/dfplus/.
A free version for evaluation and non-commercial applications can be downloaded from here : http://www.numerix-dsp.com/free/.
If you have found this solution useful then please do hit the Google (+1) button so that others may be able to find it as well.
Numerix-DSP Libraries : http://www.numerix-dsp.com/eval/