Installing dedicated 10 gauge lines

The absolute most that you need (unless you have something most unusual) is 1 (one) 20 amp circuit.  That requires 12ga with ground from your panel & a 20 amp breaker.  Use a hospital grade outlet.

From that single outlet use a 15 amp or 20 amp multi outlet strip to plug in all of your gear.  Note: The only grounded component should be your preamplifier.  Use cheater plugs for everything else.  Otherwise you will be chasing ground loops to no end.  If you don't have a preamp then you will have to experiment.

One 20A line is certainly an option. And 12g is fine for short runs from the service panel. But to recommend grounding one component and using cheater-plugs all around is irresponsible.

And the theory for using one dedicated line is to prevent ground-loops. With all components tied to the common grounding buss bar there should be equal ground potential (impedance) unless one of the components is not using a proper grounding scheme.

Not sure why people all seem to want a 10 gauge wire. You only need 12. Also If there is no room for a breaker, use a "piggy back" breaker. It is two breakers sandwiched together that only takes up the space of one breaker. Remove an existing breaker and install piggy back breaker. Be sure that piggy back breaker includes the amperage of the breaker removed. They come in 20A/15A, 20A/20A, and 15A/15A.

Seriously, you could consider more efficient speakers (not everybody needs magnaplanars?) or a more efficient amplifier (what about class A/B instead of class Y?), instead of ripping out your walls to try to do all of this.  I mean, if your amplifier has a top-grade power supply and regulator, any minor voltage drop from the wall conduit should be erased by the conditioning circuits in the amplifier.

WOW...  Lots of opinions here on power wiring etc...  I do agree that confiding in a good electrician especially one with re-modeling experience is a reasonable thing to do.  I re-modeled a retirement cottage last year and was easily able to install 10-gauge cryo'd Romex to Pangea outlets which accept the 10-gauge wire easily to a 20-amp breaker at the panel 30-ft away.  With no-load on that circuit, then powering up all of my equipment (including class-A amps) the voltage drop was ~1-volt no load to full equipment load.  My audiophile friend with roughly similar equipment and 14-gauge wiring with similar distance to the panel with full load experiences a ~3 - 4 volt drop.  So I feel that 12-gauge Romex would be fine unless you're going a good distance from the panel.  Then 10-gauge in my opinion would be better.  This was not a scientific experiment...  Just an observation on our parts with voltage-drop.  

Again, if you can measure your no load to full load voltage drop with existing wiring, you may not have any problem at all.  Using better quality outlets just makes the connections a lot more secure.  

I have been planning a dedicated AC line for some time and it should be installed within a couple of weeks. At first, I thought of using the man as a consultant who did M.Fremmer’s which was a major fix including a new meter box, new incoming outside line and junction, two outside grounding poles, etc. Since code in my area doesn’t allow anything outside to be changed, I decided on a more basic rework of my inside line.

For that, I bought 50’ of Oyaide high end cable and two Oyaide outlets with heavy faceplates. Just this was $4500. And my electrician will be able to run the wiring through the attic for about $800. Waits to be seen if I will still need my top line Shunyata conditioner. It is recommended that the amps go into the wall outlet.

I will see if the preamp is better to the wall or to the conditioner.

My current AC for the system is on the same line as the fridge. I expect that the new line will bring the whole system up to a new level. More present? Hope so.