As Ghostrider indicates, if the pre outs are part of the main signal path (i.e., if they are jumpered to the inputs of the power amp section of the integrated amp), the result would be a mono signal going to BOTH the main speakers and the sub.
If the pre-outs are separately buffered and are not in the main signal path through the integrated amp, using a y-cable will PROBABLY work ok. But I would first check with the manufacturer of the amp, to make sure that connecting the two outputs together will not cause damage or compromise long-term reliability. It's usually ok to do so, but conceivably might not be depending on the design of the buffer stage.
A mixer, with high input impedance and low output impedance, would be the most ideal solution.
Regards,
-- Al
If the pre-outs are separately buffered and are not in the main signal path through the integrated amp, using a y-cable will PROBABLY work ok. But I would first check with the manufacturer of the amp, to make sure that connecting the two outputs together will not cause damage or compromise long-term reliability. It's usually ok to do so, but conceivably might not be depending on the design of the buffer stage.
A mixer, with high input impedance and low output impedance, would be the most ideal solution.
Regards,
-- Al