Room EQ

I use Fuzzmeasure with a Behringer ECM8000 and E-Mu 0404 USB Mike amp - it is a very similar setup to Room Eq Wizard. Measurement plots are displayed on my virtual system. I use it for bass calibration to the sub only - speakers are run full range without any EQ. Fuzzmeasure uses a chirp or sweep which I prefer for running tests (very quick).

I suspect something like this is essential once you have done all the acoustic treatments that you can accept aesthetically. It certainly helped me correct for what was too much bass and too much room modal response at certain frequencies.

I'm using E-Mu 0404 USB. It is nothing special - although it does have 24 bit capability - but honestly you really don't need anything special for in room bass measurements and the ECM8000 microphone is good enough. I am not sure is if the room EQ wizard allows averaging but a useful feature of Fuzzmeasure is the long 10 second sweeps which you can also average as many times as you want. If you want to get accurate RT60 measurements down to 20 Hz then you need a quiet room to begin (all AC's, furnaces, dishwashers, laundry off and nobody moving around the house) AND you'll likely need to do some averaging (noise level goes down as the square root of the number of repeated measurements and remember that RT60 is the time to decay to -60 db SPL and that is very very low when dealing with bass frequencies that tend to hang around as well as pass through walls).

Remember that your analysis plots cannot see below the noise floor - although our evolutionary honed ears/brain can usually pick out harmonic structures about 15 to 30 db below the same noise floor.