Sorry if this has been hashed over in the past, but are 9 volts of external power too few for a pair of Audio Technica AT853(u) cards for recording moderately loud jazz in a small room, particularly regarding bass or bass drums--or are these mics happier with 11 or 12 volts? I bought these used and am unsure if they have the low-sensitivity mod, although the large RA plug suggests that they do. In the past, they have seemed a bit stressed recording loud drum solos in large rooms with 9 volts of power, despite reasonable recording levels on the recorder. Again, sorry if this has already been beaten to death.