When I built my room, I added a riser for the second row of seats. I use that volume as sort of a plenum to accept the air from the HVAC and slow it down. I put two floor vents in the riser, and although the HVAC is still audible, it’s a good 10+db quieter than when I just had one vent in the wall.Mark, I have an issue in my house when listening to music, that perhaps you've considered or is not a problem for you, just thought I'd mention it. We had a new 5 Ton Trane A/C installed about a year ago, and even though it's much quieter than the other unit; when it's running it puts out enough low level (white) type noise to irritate me when I'm trying to do some critical listening or for quieter Classical music, etc. So I have to turn it off (we like to keep the house at about 74 deg.) or wait and pause between songs when it's running. On these hot California days, when it gets 90-110 deg. in the Sacramento area outside, it will run a lot! Now I know you live in the bay area, so that may not be as much of a problem, but the blower runs to heat the house also. Not sure what could be done to mitigate that. It comes on so often on hot or cold days you get acclimated to the noise and don't normally even notice it.