If all speakers are set to large on your pre/pro, you shouldn't need to set any filter on the pre/pro -- the sub should only get the LFE signal. Large by definition means the pre/pro doesn't do any bass management to the speakers (so even if it offers the option of adjusting the crossover, there shouldn't be anything actually happening). I don't know what the enhanced bass is doing, so you may just have to try with and without it to see what you prefer. I'd probably start out with it off, but that's just me.

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