Running a pair of Sierra-2EX with a Yamaha A-S301 Integrated Amplifier. Sub out from the Yamaha to a rackmount subwoofer amp that's giving my passive 10" sub 400 watts @ 4 ohms. I like the sub amp and I like the sub (DIY build) but it's too loud. The sub amp has digital controls that dial down to -9db but that's still not low enough to balance with the Sierra's. It doesn't sound BAD by any means, it sounds great, it's just not balanced and really should be lower. Is there any way I can gain control of that without replacing the amp? Anything that could go in-line to the sub to attenuate it?