a-them AVM 90 Operating Manual page 39

Channel Levels (Subwoofer, Front Left, Center, Etcetera)
If you're calibrating by ear, use the remote control and sit in the listening area. Adjust each channel's loudness until
all levels sound the same. If using an SPL meter, adjust the level until it reads 75 dB for each channel. If Front Left was
at 0dB when you set Dolby Offset / Calibration Level, then no adjustment of Front Left is necessary. If using a powered
subwoofer, adjust the sub's built-in level control before setting the subwoofer level in this menu or using ARC.
Speakers set to "Off" in the Bass Management menu can not be adjusted. Note that if ARC has been used to set levels
and is then turned off, the subwoofer level should be reduced by the same amount as room gain, or else you'll hear
elevated subwoofer output.
Multiple Subwoofers
If using multiple subwoofers, you should balance them with one another before calibrating the rest of your system. If
using ARC, use the Quick Measure function to help find a flat response as a preliminary step before running full
measurement. If setting up the traditional way, play the subwoofer test noise with only one subwoofer connected at a
time. If using two subs, set the subwoofer's built-in input level so that the SPL meter reads 71 dB from the listening
area. Target 67 dB If using four subs. Repeat this for the remaining subs, balancing each to the target level. With all
subs connected at the same time, the result should be around 75 dB. Make the final adjustment in the level calibration
menu.