A separate 20 amp circuit should be fine. Even wih higher power amplifiers it's unlikly the peak current will trip the circuit breaker ~ especially with Klipsch ~ less efficient speakers are another matter. In the old days we had things like reel to reel tape decks with three motors each and whatnot, so there was much more current required at times.
What you really want to do is put that dedicated circuit (or two, if needed) on it's own isolated ground. Ground only the power supply, or control center, or whatever it is that your going to plug all this into. The system should be grounded at only one point. Don't directly ground the rest of the components. Let the ground "float" among them and seek it's own level. Use a 3 to 2 prong adaptor on all the remaining components if necessary. This will avoid ground loops which are the source of most noisy grounds.
Forget the extra insulation if you're concerned about blocking sound (sound transmission). Absorption is one thing. Sound transmission is a different problem. In order to block the sound you need to literally block it with lots of mass, or isolate the room//wall/structure. What Mike Hurd suggested (staggered studs) is the minimum starting point for this. If your new "custom" home is being built by a large tract home builder/developer like Ryland you'll most likely find that they are not up to the task of making these kinds of changes.
Many light dimmers will emit RFI (radio frequency interference). Make sure the ones you choose are certified against RFI. RFI is "air bourne" so to speak, so simply putting the lights on a separate circuit may not eliminate it. Also, avoid low-voltage lighting systems as they tend to generate mechanical noise (transformer hum).
Klipschorns R&L 76, Belle Klipsch center 79
trio of Luxman MB3045 triode power amps,
Audio Research SP6B preamp,
Linn LP12 w/OriginLive Ultra PS&motor, Morch UP4 arm, & Decca Jubilee pickup
Thorens TD125MKII/SME III/Shure V15-Vmr
McIntosh MX130, Nakamichi Dragon cassette deck, Sony A7 Digital audio tape deck
Shanling SCD-T200 sacd player, Denon 600F cd player
Topaz Line2 power regulation, Furman power conditioning/monitoring; and of course, the proverbial, dedicated, acoustically tuned, listening room