A:Answer This receiver has 2 LFE out's. This is a pre amp out meaning it is just a processed signal that carries the Low Frequency information without being amplified. Because this is not amplified a powered subwoofer must be used to amplify the signal. Moral of the story is since the subwoofer uses its own power and doesnt use any of the receivers power, you are not limited on size, power usage or efficiency. But your room size and characteristics will be the ultimate judge of subwoofer size. Remember, with subwoofers bigger rarely means better. Look for build quality, quality of materials over size as these will affect the subs sound more than size will.