The diffuser cones are interesting, it would also be very interesting to see the SAW waveguide version measured. This is the same style waveguide that B&O still uses. Or perhaps a Beosound implementation would be a better choice to evaluate the concept just because it is more modern. Canon S-25:
Given the general terribleness of almost all measured AVRs and preamp/processors I'm assessing other options for living room audio. To that end, I have compared the signal from a Marantz 6012 to the signal from an "Orei 4K 60Hz 18G HDMI 2.0 Audio Converter Extractor ARC Support" to Topping...
If you are taking requests, a DAC with built in user programmable DSP/PEQ would be great. RME ADI-2 DAC seems to be your only competition in that space. I just ordered the RME. If only there had been a cheaper option with equal or greater DAC performance with equal or greater EQ options...
In addition to the level shifting devices already mentioned, there is the Samson S-convert (possibly no longer made) and the ART Cleanbox. When I was trying to accomplish this years ago to use a pro amp for a diy subwoofer, I came to the conclusion that I could either get a passive device and...
Regarding what measurements might be useful; power vs. frequency seems like a low qualification bar (i.e. necessary to measure but an unwelcome surprise if an amp fails). We work hard to have flat frequency response with low distortion as a musical signal passes through our whole equipment...