That would depend somewhat on what output gain the cmoy was set for and what sort of battery the amps use. The Total Airhead might win if it is one of the new ones designed for higher impedance headphones.
The crossfeed is a matter of taste, some people like the Meier crossfeed, some people like the Headroom crossfeed, and some people like no crossfeed at all.
HI: I have both the total airhead and the cmoy 2-9 volt amp. The t/a couldnot power my 580s or even my philips 890s but did great on my koss-35s. The cmoy can power my 580s and my philips 890s to a good sound level and it sounds much cleaner than the t/a. So for me the cmoy is light years better than the t/a.