No one actually knows how to lculate what speaker cable they need

I am an engineer and designed chemical, electrical, and mechanical products. I am retired. Designed cables for instrumentation since the 80's, started recording in the 70's. The design your are suggesting might be Ok for the entry level. I would suggest that you try Oxygen Free Highly Conductive copper for your cabling. If you can not hear the difference maybe you should have your hearing checked.

Mr. tom1000

Thanks for your advice. It is not my design. It is my calculated wire with a resistance values to fit the amp's output resistance. Your OFC been grounded thin already on this thread. After all you are a late comer. A normal cooper wire is 99.8% pure (by industry standard). The OFC (Oxygen Free Highly Conductive copper), has only 0.1%-0.19% better conductivity than the ordinary wire. In my calculation it is negligible. In real life, no one can hear that difference. The OFC and purity are just to get you pay more for something that does the same job. Go for it. I'll spend my money elsewhere.

Mr. viridian

Thanks for your incite. NAIM is special. Nothing is standard with that firm and products. They have a special interconnect (not RCA and not XLR): a 3 pin DIN with bayonet. They have a look of a badly painted black shoebox and a price of bankrupt! with a green light that reminding me the Saudi flag. So is their approach to the speaker wire and interconnect cables. Buying a naim system is a closed case in deed, because it is a catholic marriage. They force you to keep with naim. They went a bit too far with that, so they turned into a cult. Like a new religion called naim! You need to join it, learn the naim bible and live by that. A tiny slip and you are out. I see you are already a preacher of that bible.

I don't like to be forced. I don't like cults and I don't like naim. Case closed.

I would like to see what you can do for me:

Croft Pre / ATC P1 power into harbeth 30.1 ... setup on side wall so need 4.5m length

Lets see how wrong I was/am

The ATC P1 power spec does not specift DF. A Q was sent to ATC. They do not answer the phone!
What cable do you have? (AWG and length).