Inversion is one way to do it. It's simple enough, but I am finding that I am more impressed with the sound through filters made with the EQ tools. They are both effective, though. Perhaps it is the way that the filters are exported. I need to get confirmation from John on what is happening, but basically this is what I have been doing for quick filter creation:
• I use the Generic Extended equalizer to create my filter set.
• From the filter tasks panel, I select Generate measurement from filters.
• Once both channels have been assigned filters and I have both sets in REW as new measurements, I export them using File > Export impulse response as WAV, selecting stereo IR and assigning the filters to their associated channels.
Yes, I could simply export the filters' impulse responses from the filter data without turning them into measurements. However, doing it the way I have outlined here allows you to export a minimum phase version of the IR, which always sounds better to my ears than exporting as measured. If you export the filters impulse response as WAV, you do not get the option of exporting a minphase version.