renov8r,
Those are nice articles. You're right, there is a little bit of snake oil in the Dirac and MultiEQ articles but the Mellor articles are very good.

Back in the late 80's some friends and I built a prototype FIR based equalizer. The advantage being that FIR filters are linear phase and thus you can have multiple filters at different frequencies that at the end of the day all sum up with the same group delay. Back then each filter circuit was the size of a pizza box and not very practical. Alas, we did not patent the idea...(End old man rant)

Everyone is touting their particular solution. In all honesty both IIR and FIR filter have their pros and cons. A FIR filter depends only on the input data to calculate the output. The IIR filter uses the input data AND previous output data to calculate the output (i.e. it uses feedback). And THAT is the only real difference between the two filter structures.

The problem with feedback is too much can lead to oscillation. This is great if your name is Ted Nugent, but not so great for home theater. However IIR filters are well understood and can be designed to avoid oscillation.

The other issue (not necessarily a problem) is that IIR filters have non-linear phase. I'm not going to get into Z-transforms which explain why the phase is non-linear. However I will say that I have never seen anything that explains how much non-linearity has to exist before you actually hear a difference.

To say that a FIR filter is better than an IIR filter just because it's a FIR filter is misleading. As always, it's your ears that should make the determination.

Oh, btw, the impulse response of your room is what it is. Unless you change your room (treatments, carpeting, adding more people, etc.) you aren't going to change it's impulse response. Any filter you add/change to your system is going to alter its impulse response, so yeah, everyone is modifying the impulse response of their system whether they call it that, or not.

Yes, it will be interesting to see if the new processor has room correction. I'm still thinking "No".