I peg a calibrated 120dB SLM at 16Hz/400W in-room, and we're talking about Southern stick built here, so there's not much gain. My neighbors down the road know when I'm playing organ music.
With two, well, I've literally loosened the rafters, and am currently adding some bracing. I've pretty much given up on keeping the drywall looking good. Seams are split all over the house, with old nails and new screws alike popping through. Yesterday I noticed a split along a seam in the concrete block foundation.....
Oh well, life is just a bunch of priorities/tradeoffs.....
GM
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Loud is beautiful, if it's clean