My home theater system is based on the use of an Oppo 105 without a theater processor. It is connected directly to my five channel amp via rca interconnects. Is it possible to connect my subwoofer LFE directly to the Oppo 105 subwoofer output without having to use a processor? I've connected everything properly but not getting a signal to the sub. Subwoofer is on in the speaker set up. All speakers are set to large which defeats bass management. Any help would be greatly appreciated!