I thought I'd get the ball rolling from
It would be great if those with REW would do a simple loopback of their AVR, PEQ, Pre/Pro, amplifiers, etc. and post them is a thread dedicated to signal chain loopback measurements. It's so easy to do, I wonder why everyone doesn't do it. REW is free and you don't need a mic or anything else to do the loopback.
basic process is just to take an output from whichever device you're measuring and then feed that back to your soundcard (taking due care with levels if measuring an amp) then take a measurement in REW. A few things to bear in mind;
* make sure you have an appropriate (soundcard) cal file loaded to counter any purely measurement artefacts (e.g. a hpf on a line in is not that uncommon)
* If your measurement covers multiple devices (e.g. perhaps you first loopback over your bd player and then you loopback over your bd player + processor) & you have a measurement for each stage then you can use the "A / B" trace arithmetic function to see the contribution of each individual stage