\rHI Vincent:
If you need to operate both amplifiers at once you will want to check out either our SSVC2 2 zone speaker selector with 2 internal Volume Controls or our DSM4 a 4 zone speaker selector both which feature independent source A or B switching per each zone. So you can play A on both pair of speakers or Source B on both sets of speakers. Plus you can play source A on one pair while listening to source B on on the second pair of speakers. The DSM4 will allow you to expand to 4 zones and add optional external volume controls for each pair of speakers for the best impedance matching protection. The DSM4 has internal protection but when enabled it cuts the power handling in half from 140 watts down to 70W. There is also the SSVC4 which is 4 zone , 2 source and includes four internal impedance matching volume controls.
Good luck
TL/4581\r