Thanks to Owner-Manuals.com! This manual was exactly what I needed. As Amana was purchased by Maytag and later by Whirlpool, there was no way to receive it from their websites. I was lucky to find this resource.
Great to be able to set channels again, on an old but stoll fine working TV
Text excerpt from page 9 (click to view)
OPERATION STEREO STEREO mode is the most frequently used mode among the three. Each channel is independent of the other, carrying its own input signal, with its own gain control. Stereo mode comes in left and right channels (See Figure 5). A) When one channel is assigned for left channel, make sure the other channel is assigned for the right. B) User can use the unit for mono output, with one as main and the other as monitor. C) This power amplifier can also be used for biamplification. One channel for driving low frequencies while the other for driving high frequencies.