A-2.1 3 channel Stereo amplifier

1. Which input is better?
The RCA inputs provide better contact. If only 3.5 mm plugs such as for operation of PC or MP3 are used, the RCA inputs are automatically activated.
2. How do I adjust the controls?
First all controls should be set a 7 o'clock, then turn the MAIN VOLUME to approximately 8 o'clock depending on the power handling capability of the satellite speakers. The bass of small satellite speakers may be effectively adjusted by the SUB SONIC by continuing turning further to the right until the bass is slightly reduced and even further if speaker diaphragm excursion creates distortion.
Adjust subwoofer as follows:
SUBWOOFER HIGH CUT at 9 o'clock. Turn SUBWOOFER VOLUME control slowly clockwise until the volume ratio of the subwoofer and the satellite speakers are correctly matched. Small subwoofers may be adjusted in this manner, turn SUBWOOFER SUBSONIC slowly to the right until the low bass volume is slightly reduced, then back off 3-4 mm= idle power is filtered resulting better reserve power. In case of a misalignment between the high bass of the satellites and the subwoofer, the SUBWOOFER HIGH CUT control should be turned further clockwise. This results in more upper bass volume of the subwoofer, however avoid turning the SUBWOOFER HIGH CUT too far to the right as this would result in an increase of the mid range of the subwoofer which would subsequently reduce the stereo image.
3. What speaker options do I have?
The 2 ohm capability of the subwoofer output allows connection of two 4 ohm speakers in parallel in one box. In the event one 4 ohm subwoofer is used initially, a second speaker may be added later.
Another option is the use of two speakers each equipped with one 4 ohm chassis in parallel and a crossover point at approximately 60-70 Hz to a 2 way full range speaker.
All variations have distinct advantages.
a. reduction of cost as crossover networks are not required. Elimination of poor sound quality caused by inferior crossover networks.
b. speakers can reach their full potential sound quality due to the filter characteristics provided by the amplifier.
c. the variable SUBSONIC filters allow higher sound levels of smaller speakers without distortion.
d. speaker design changes do not require new cross-over networks as only control changes on the amplifier need to be made.
e. the variable controls of the amplifier can simply be used to change the cross-over frequencies from the bass speaker to the satellite speakers.
4. Can I save the cost of purchasing an additional subwoofer?
Yes, if you consider the following:
a. You can use an existing passive subwoofer if it is switched from SW on the A-2.1 to the subwoofer of the existing system, however this will not work with an active subwoofer because the built in amplifier can not be bridged.

CAUTION never drive a common speaker with two amplifiers simultaneously.