Regarding the Connex power cord. They are going to be low cost tinned or OFC copper, and they are going to be stranded bundles of wires for each conductor. The plugs are going to be low cost brass plugs. Gold plated will give a slightly warmer sound with softer highs. You could try them if you wanted to, but there are better options.
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If you wanted a decent power cord in this price range, I would look at the Pangea power cords from Parts Connexion. They are mostly solid-core or litz wires with good gold-palted copper plugs. You can get a 9 awg cord for the amp if you want. I think this will be about the best you can do, but expect to pay up to $199 or so. I consider this a "final buy" power cord because the make-up of the litz polymer coated wires makes it extremely difficult to chop and re-terminate with a better IEC or male plug. But if you wanted the best power cord in this range, this is what I would recommend.
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You can try either above power cords for your amp (Pangea would be better). For the Marantz, I would give this a try:
https://www.ebay.com/itm/AudioQuest-NRG-5-AC-Power-Cord-Cable-2m-6FT/142991388935?hash=item214af37107:g:xg0AAOSw0QBb1LQg:rk:36:pf:0
The NRG-5 is all solid-core OCC type copper with very low restrictive insulation. It's really a 14awg power cord, but the best quality. It does have gold-plated copper plugs, so if it's not detailed enough in the sound, you can always chop the ends and cut/strip the wires for a new Furutech silver-plated or rhodium-plated IEC plug.
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If you wanted a decent power cord in this price range, I would look at the Pangea power cords from Parts Connexion. They are mostly solid-core or litz wires with good gold-palted copper plugs. You can get a 9 awg cord for the amp if you want. I think this will be about the best you can do, but expect to pay up to $199 or so. I consider this a "final buy" power cord because the make-up of the litz polymer coated wires makes it extremely difficult to chop and re-terminate with a better IEC or male plug. But if you wanted the best power cord in this range, this is what I would recommend.
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You can try either above power cords for your amp (Pangea would be better). For the Marantz, I would give this a try:
https://www.ebay.com/itm/AudioQuest-NRG-5-AC-Power-Cord-Cable-2m-6FT/142991388935?hash=item214af37107:g:xg0AAOSw0QBb1LQg:rk:36:pf:0
The NRG-5 is all solid-core OCC type copper with very low restrictive insulation. It's really a 14awg power cord, but the best quality. It does have gold-plated copper plugs, so if it's not detailed enough in the sound, you can always chop the ends and cut/strip the wires for a new Furutech silver-plated or rhodium-plated IEC plug.