Nice looking setups, RedSI.

You know, if you wanted to revisit your wall construction project, you could potentially cut a small recessed "cubby" into that knee wall and tuck the RBH into the shelf just below the cap. Feed the speaker wire down inside the wall and maybe under the carpet, and it'd be a pretty low-profile installation.

I'd be curious to hear what you think of the Mitsu AC system if you do get one. I've spec'd a couple of this little units for some odd spaces recently (none of which are actually in place yet), and the technology is intriguing. You might also check into Daikin to see if they've cropped up in your market yet - they are a big competitor of Mitsubishi's in the Asian HVAC market, and they have some equipment that is very similar to Mitsu's (variable refrigerant flow, multiple zones sharing a single condensing unit). Both have the potential to be good approaches for adding HVAC to an older home like yours.