Synergistic Research AC Master Coupler on all Components including Subs Over-Kill

Used I would lean towards the Tesla, especially because I know how easy it is to have the Active modded, either DIY or Michael Spallone, and how much improvement that will be.

Element Tungsten would be a good choice if you care a lot about midrange and want it as beautifully detailed and yet smooth and deep as can be. CTS is better- Copper improves the bass, Silver the top end- but Tungsten is awesome with midrange.

In terms of new the Atmosphere line is awesome. My Atmosphere Level III interconnect opened things up to a whole new level. I've heard a lot of Ted's stuff over the years. Nothing negative about the rest but nobody his record over the years is such that you cannot go wrong. There's little details like MPC mods but aside from that you can pretty safely assume that the more you pay the better you get- which is not at all true across the industry.
Where I think it gets hard is allocating resources. Alive is a lot better than Blue. No question. But $350 better? That would buy you two Orange Fuses. Which an Orange Fuse at $160 is way better than most $500 power cords.

That's about it for me. Last thought would be, just call Ted. The guy loves this stuff and fully believes in my style of bringing everything up to around the same level. Call and tell him what you have, your plans, your preferences, let him help you out. Maybe not so much if you want to go used. Although maybe even then. From what I have heard he is the kind of guy if he thinks a Tesla or other used cable is the way to go he will let you know. But for sure if you will be buying new.

Wow. So you pay big money for stuff that does nothing for you, and then advise others to do that too. Amazing! Well at least you're honest about it! 

In practice of course simply finding these takes a while, meaning plenty of time to try them as they come in one at a time. The first one would usually have the biggest effect from the wall to the conditioner, because then everything downstream gets the benefit. Then usually the last place or least effect will be on the subs, because power cords are all about timing and resolution and there just isn't all that much of those at the bottom end. 

What you should do OP is keep a look out for SR power cords in general. The Master Coupler, while it is kind of the industry gold standard for having been around for 30 years and yet good enough to still be better than a lot of more expensive ones even after all that time, while that is true it still nevertheless is the bottom entry level from Synergistic. Everything they've made since is better, a lot of it so much better you wouldn't believe. Because of this, if you see anything SR and you can afford it, go for it. 

Power cords are just like everything else- the better they are the better the sound. Which is all that matters. If you can't hear the difference, if it doesn't sound better, why bother?

1. No. Not at all. Given the level of your associated components the Master Coupler is entry level. Full disclosure, I reject the notion of there being any such thing as overkill. You could put a $10k SR cord in there and be blown away. So even that would not be overkill. It would be a misallocation of resources, which is not at all the same.

2. No its a sieve. Bucket without a bottom. Red herring. McGuffin.

3. Yes and it should be. You want everything on one circuit as a general rule to prevent ground loop hum and keep noise levels down.