Hi chax,
the Sub / Aux Outputs of the SX900 have the following specs:
[SUB 1 OUTPUT] (10kW load)
1(L/L+R): -7.1 ±2 dBu (fixed Volume, not affected by the Master Volume!)
[SUB 2 OUTPUT] (10kW load)
2(R): -7.1 ±2 dBu (fixed Volume, not affected by the Master Volume!)
The Main Outputs have the following specs:
[MAIN OUTPUT] (10kW load)
R: -1.2 ±2 dBu (@Master Volume dial set to the the maximum position)
L/L+R: -1.2 ±2 dBu (@Master Volume dial set to the the maximum position)
P.S.
To connect an external (active) Subwoofer to the SX900, the MAIN Outputs should be used (or only the MAIN L/L+R socket if a MONO Subwoofer is used).
The SUB / AUX Outputs are not suitable for connecting a Subwoofer as these Outputs are NOT affected by the Master Volume dial.
Best regards,
Chris