Waayyyyy… over thinking this.
First, IMO, all your electronics, digital or otherwise should be on the same circuit due to the greater evil of a ground loop. A 20 amp circuit is a ton of power. As I noted above, I personally experienced the evil of splitting across circuits just last week so… believe it or not, your call.
2, I can’t believe why a quad is different than a duplex… look, I am an audiophile nerd since the mid 70s… I get it… do it right, sweat the small stuff… but quad vs duplex… well you get my opinion here. That is simply silly in my book. A quad just gives you more outlets should you need it one day… incremental cost is insignificant…evan-K has it correct.
Go ahead an put in two circuits, split the load and if you think it sounds better that way, you win.
BTW, cheapest I have seen for a short run is $250… expect $350… if you live in a special zip code, you will pay $500 and up… depending how clueless you are. Sorry, don’t mean to insult anyone here, but the people in my zip code are all dopes… they get ripped-off hourly. I think I am the only person within a 10 mile radius with automobile jack-stands and tools who actually can turn a screwdriver.
Regarding the load capacity of a 20 amp circuit… 20amps X 120 volts = 2,400 watts available (ohms law). Then, as a rule of thumb, don’t load a circuit beyond 80% so 2,400 X .8 = 1,920 watts available. Now look at the specs of each piece of equipment and it will show the power consumption (this is a non-real world max… real world is much less). Then just add up the power consumption specs for each.
So DirectStream DAC = 30W, A BHK 250 amp (a monster) consumes 850W at 8 ohm… (these are non-real-world number… real is way less)… so now we are at 880… and you have 1,920 and that is at 80%… said another way, a 20 amp circuit could kill Godzilla. For 15 amp circuits, just substitute 15 for 20 and rerun the math, So for all you 15 amp wimps out there, fear not, your cuircuit could still kill an entire invading army of Japanese monsters on any Saturday afternoon.
Now a big evil is not-having a dedicated circuit… that is IMO the biggest issue as noises from say an electric motor or dimmer, or Her hairdryer… dedicated can help (but only helps) and IG gets you way further from noise, a PS Audio regenerator makes life nice… owning your own Nuke plant is really where you want to be.
Bruce in Philly