Hi dilznik,
Yes, this is possible! You need a Trigger Box that can generate the required signals to switch the speaker out of Standby mode, so that it can accept the variable-line outputs from the surround sound pre-amp. I can provide suitable Trigger Boxes for use in UK and Europe (countries with 220-240 volt AC power supplies), but I'm not sure where you are located so my product may or may not be suitable for you.
You are correct that Beolab 7.1 is a stereo speaker, hence (depending on the options available for the specific pre-amp you are using) I would normally feed it the Front Left and Front Right signals from a surround system, then tell the system that there is no Centre speaker fitted. If the Centre speaker cannot be disabled on the pre-amp, the other option is to feed the Centre channel to both the left and right inputs of the Beolab 7.1, making it a very powerful mono Centre speaker instead.
It is worth bearing in mind that not all Onkyo and NAD models have RCA pre-out sockets, the more basic models normally just have passive speaker outputs. These can still be used with Beolab 7.1, but ONLY with Attenuated Cables to reduce the signal levels and prevent any damage to the speaker.
Kind regards,
Steve.
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