Originally Posted by WarmongerX
To those that have used REW, is it worth the time, effort and investment to get the $95 mic and spend time learning the software? Or is using the receivers built in calibration tools (MCACC, Audyssey, etc) + SPL meter + some manual fine tuning a better route. I've been reading about it for the past day and it seems easy and complicated at the same time and I'm wondering if it's worth the effort and hours spent configuring everything.
Will you hear the difference between either way?
Using REW and using AVR calibration tools are entirely different things. Every listening room has audio characteristics that affect audio quality. The placement of your speakers, and the amount of room treatments can correct for audio issues. REW is a tool to assess the audio quality and assist you in determining whether adjustments in speaker placement and treatments are resulting in improvements.
Any thing you do to get your listening room in the best audio shape before you run automated room correction, the better the correction results will be. But REW room-tuning does not REPLACE room correction. If you have automated room correction, you should still use it, because it is the "icing on the cake" that corrects other audio issues that cannot be fixed with speaker placement and treatments.
So, long answer, but the proper approach is to use both, because they compliment each other.
Edit: I should add that using both REW and automated calibration together always results in a better solution. Unless you have an exceptionally good listening room, automated calibration by itself rarely corrects all the audio issues.