Got big amp-help with 20A line and receptacle

So, I just purchased a Krell FPB 400cx, which I'm told requires a dedicated 20 amp line. Yes, I have read some Agon threads on running dedicated lines, as well as 20 amp receptacles. But they are mostly several years old and I am interested in some current basic recommendations.

I am not looking for the most expensive or esoteric setup, but do want to do it as best I can. The receptacle location is in the family room, which I estimate will require about 50-60 feet of cable from the breaker box in the garage.

So, at first all I knew was that I would be running a new line from the breaker box and that it would be grounded there. But some posters here and elsewhere stated that I should have an isolated ground installed outside the house and at least 6 feet from the existing ground. There were also suggestions around exactly which location IN the breaker box to place the new line and breaker.

We do have three refrigerators here, one in the kitchen, one in the utility room, and another in the garage. Of course, we we have all the other typical appliances in the house. One good thing is that, in my current setup with no dedicated lines, I don't hear any noise through the speakers unless I use the dimmer in the family room. So, maybe the power in the house is pretty decent.

With regard to receptacles, I've read various comments about the different brands, as well as the various effects of gold, rhodium, or other plating. To start with, I would like to try the most neutral sound I can get.

I did speak with two electricians today, and neither seemed to have much familiarity with the considerations for audio quality that I mentioned to them. Therefore, I would like some input on what to ask of them. If I am making this too complicated and harder than it needs to be, I'd like to know that as well. I would really appreciate any tips and input!