Saki70, you've received good advice from some of the posts above. Running the two dedicated 20 amp circuits will be the biggest gain for you. Installation choices that will enhancing those dedicated circuits would include:
..Use 10 gauge wire
..Make the leap to using an isolated ground in your wiring (which means using the hospital grade connector that will not self-ground when installed in a metal box, and 4-wire cable with a ground wire -- I think the current color-coding standard is for that type cable to be manufactured in a green sheathing)
..Get both dedicated cables run to the same phase of your electrical panel, if you can. And try to put them on the other phase from heavy-duty motors and compressors: often easier said than done.
..Use non-plated all brass receptacles, as Rcrump suggests. Hubbell makes a non-plated all-brass hospital grade receptacle, but I can't find the part number right now. Pass and Seymour may have something comparable. Definitely try to stay away from nickel plated parts.
Or use one of the receptacles from: Jena Labs or Walker Audio or Albert Porter (if he still has any, often referred to here as "Porterport", a cryo'd Hubbell). The Jena Labs and Walker Audio receptacles are special production runs by Hubbell using their 30-watt chassis for heavier gauge internal parts, no steel and no plating, configured as a 20-watt receptacle, then cryo'd like Albert's. Other people will have had experience with other "audiophile" receptacles, but these would be my recommendation.
..Get some SST silver contact enhancer from Walker Audio for your electrician to use on all the connections in the circuit. Your electrician will be familiar with electrician's paste: explain that this is just a much higher grade, higher quality paste (which it is, by a huge margin). Then also use it on your power cords, interconnects and speaker cables. Try it on you main system and I think you'll be amazed at the improvement.
This is a summary coming from my experience; it's worked well here.
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