I’m not even approaching reference levels (usually my level is at -12 or so) as my current speakers are super easy (Klipsch), but for now the circuit is not dedicated to the Cinema 40, it has to carry also a 2Ch Onkyo 5010 powering my mains, my 77” OLED, my PS5 (plus my Blu-ray, turntable, phono, and Apple TV, but these would not be ever used at the same time as the PS5)
I can almost guarantee you (would put my engineer's stamp on it lol...) that you will still be fine though if everything gets to turn on at the same time, it could trip your breaker once in the blue moon when the instantaneous current might reach a huge value (many times, like >20 times or much higher of the rated 15 A). That sort of condition could happen but very unlikely.
I prefer to use dedicated circuit for the mid, especially upper mid (your Marantz) and flagship level such as the TX-NR5010 (if yours the little 2ch M-5010 then no problem), but that's mainly because I like to follow best practices.
So far I thought that based on the labeled wattage on the back of the devices I’d be fine (710 for marantz, 150 for onkyo, 160 for TV, 200 for PS5, ~50 for Blu-ray player, so a total of <1300, so even at peaks safely lower than the 1800 limit), but now I realize that the AVR which drives the rest 9 speakers could in theory reach well over a 1000 at times (probably not with my listening habits though).
I’m wondering, playing near the limit of 1800 could compromise your wiring, or the fuse will kick in before it gets dangerous?
Those labels are only useful for comparing units within the same brand/model lines, because different manufacturers may follow different rules/standards/best practices etc., or even just their own.
Denon and Marantz follow some sort of existing standard and the best write-up I could find is one published by Gene of Audioholics.com and I have posted it a couple time before, sooner of later I need to book mark that great article for D+M users, so I don't have to search for it every time I want to post it for them.
Since you have the Marantz, you really should read it:
Ever wonder how your favorite manufacturer rates power consumption on their AV receivers and how it relates to maximum available output power to your speakers? The answer may surprise you so read on.
www.audioholics.com
Especially the following section:
Marantz SR8015 Example:
The SR8015 rated power 140wpc x 11 channels but the back panel power consumption is only 780 watts.
Marantz de-rates 2CH power rating to drive ALL 11 channels for the IEC 62368 safety test. In this case, 90.4 watts for ALL 11CH driven.
1/8th power (90.4 watts) = 11.3wpc / 0.17 eff = 66.5 watts
66.5 watts x 11 = 731 watts + 35 watts from HDMI, DAC = 766.5 watts < 780 watts back panel rating
Note: Our
bench tests of the SR8015 produced 100wpc x 7 ACD which would yield a power consumption of 700/0.55 (eff) 1272 watts + 35 watts = 1307 watts > 780 watts back panel power rating.
Someone on an audio forum is about to type "But wait, 1307 watts > 10% above 780 watts (858 watts). Yes they are correct, however, this is NOT a violation of the safety standard since the ACD test is NOT considered to be a "normal operating" condition as previously stated.
The sad thing about the internet/forums is that no matter how many times I post, you re-post such informative articles, people would keep on telling the internet that such and such manufacturers (could be D,M,S (Sony), Y(Yamaha), O/I/P (Onkyo, Pioneer, Integra) power outputs are BS because the power consumptions are so low based on the back labels. Those people, who really don't have enough knowledge to spread such incorrect info but they do that all the time, you wonder why we have so much fake news, misconception, hearsay, oh yeah including the so called Marantz musical/warm sound (no offence, really, happy for you that you believe you heard that), I just feel like venting a little in case I am not alone of this lol........
So, again enjoy you really nice looking and so well build Cinema 40, one of these days I may even trade in my so called separates for the Cinema 30 when I am ready to downsize, by shedding weight and got rid the cabling spaghetti and multiple big and heavy boxes that I have to carefully vacuum a few times a year.
One box, plug into one 15 or 20 amp outlet is getting tempting by the day, as someone's getting older by the day.