Confused by power rating (2024)

I bought a pair of KEF LS50 Metas for Christmas and have been powering them with a Marantz PM8006 at low volume in a medium size room.

I keep reading that LS50s need 100 watts to sound their best. Presumably this is because they drop to 4 ohms. One reviewer even outright questioned KEF's 8 ohm rating and claimed the LS50 Meta was actually a 4 ohm speaker.

My PM8006 is rated at 70 watts into 8 ohms and 100 watts into 4 ohms. So, is my Marantz actually feeding the KEFs 100 watts when they drop to 4 ohms?

Do you like the way the Metas sound?

I do. At first they seemed WAY too bright and fatiguing. Like, too forward in a bad way. I kept reaching to turn the volume down. This has gotten a lot better. I suppose break in IS real.

I have no complaints about sound quality. I'm just curious about what is happening power wise. Especially because I keep reading LS50s need 100 watts.

many times what an amp speaker match should sound like "on paper" as a caution becomes absolutely fine when you actually listen in reality.
yes, an amplifier that increases power as the resistsnce is lowered is what you have with the Marantz.
power = voltage x current
current = voltage / resistance
lot of variables determine the ear test including room size, listening levels and distance from speakers.
it is at the extremes where power to resistance matches become tested, e.g higher volume levels in larger rooms further away from speakers.
if you are satisfied then no worries.

Everything that you posted after the part I've bolded is therefore ignorable.

Don't worry. Enjoy listening.

Jeff

The specs suggest the Marantz is capable of outputting 100 watts into 4 Ohms. But is it actually doing that? Depends on how loud you listen. If you play your speakers at low volumes in a small/medium sized room, most of the time you are probably using 1 watt or less. If you play louder then it will draw more power. And peaks, at moderate to loud volumes, will require good amounts of power for short durations.

I think when people mention an amp that puts out 100 watts, they are referring to the 8 ohm rating. The Marantz is under that. But that is a generality. As above, how much you actually need is largely dictated by how you use the speakers. I'd guess the Marantz has enough power as long as you aren't really cranking up the volume.

They are rated at 40-100 W at 8 Ω (min. 3,5 Ω) , Sensitivity (2.83V/1m) 85 dB

Just means that they will max out with a 100 watts and have a low sensitivity.
You're amp is giving them everything they want. Maybe with a bit more current they will have more overhead but likely not necessary unless you want to push them near their max SPL at 106 dB.
All of this is their maximum threshold.

Im my opinion if you're looking for more from them you'd want to consider the R3 model over the LS50. 15-180 W at 8 Ω (min. 3,5 Ω) , Sensitivity (2.83V/1m) 87 dB.
Steve Gutenberg, who is a fan of the LS50's always says the better choice is the R3.

Oh, you'll also find many that will say that you *don't* need 100W too with the LS50's.

Who do you believe? In the end, like many sometimes you just have to try them yourself after getting answers all over the spectrum.

Remember, synergy plays a key role, and not everyone who posts have they're systems well integrated or set up.

So, as asked are you posting because you're not happy with the sound, or wondering if there's greener grass with a better amp driving them?

I don't think you have to worry about sufficient power. If you like what you are hearing, that is all that matters. You will not be taxing your amp at all unless you plan to recreate a rock concert at full volume (which your speakers can't do no matter how much power it is fed).

This is definitely a greener grass type of post. I think they make a great match! Still, there's this nagging voice that ponders whether an amp with higher wattage would somehow drive the speakers better.

Well, greener grass recs are right in this forum's wheelhouse but I'd need a budget to know what level of quality is available, and whether it'd be worth it then.

But I don't think you're in a bad spot with the Marantz, and if your budget gets too high in your spot I'd start wondering about new speakers then.... if you catch my drift. (that voice you mentioned)

I would guess an Anthem 225 would be a great option. Lots of power, on the warm side, and affordable on the used market - around $1K.

Just a guess though. Never heard the combo, so this guess isn't worth a lot. But the Anthem is a beast and sounds very good.

Something to consider if you're wed to power amp specs which Marantz is not, at least with their 8000 series. I believe the 8006's power amp is the same as the 8004, an americanization of the euro market's PM-KI-Lite, which was tested by Australian HiFi circa 10 years ago at close to 90 & 150 watts, 8 & 4 ohm respectively.

Thank you for sharing this. I was reading through reviews on Amazon and one guy claimed the PM8006 puts out 100 watts and had a source to back up.

"Marantz is always very conservative with their power ratings; the PM8006 actually outputs a continuous 100wpc into 8 ohms, with dynamic power handling of 128wpc into 8 ohms. These measurements were published in HiFi News magazine, September 2018 issue, page 51 — I've attached a screenshot."

https://www.amazon.com/portal/custo...dL&imageExtension=jpg&reviewId=R23LSLMP8IJV5U

Im sure those who have had amps with power meters will attest that "generally speaking" they arent usually using (granted some like to really turn up the volume every once in a while) much power to get nice listening levels. As has been mentioned, larger rooms, listening positions farther away, and inefficient speakers increase power requirements/usage. If the low end starts to suffer at louder volumes, then you need a more powerful amp.

Ive played around a good amount with B&W CDM-1SE (8 Ohm, 88 dB efficiency, 58 Hz on the low end, 30-120W recommended power) with both Luxman M120A (120W@8 Ohm, ?@4 Ohm) and Forte Model 3 (200W@8, 400W@4). Im convinced that 120W max power rating is rather conservative. The Forte could play them noticeably cleaner at louder volumes, and louder period. When I threw in a 50 Hz high pass filter with the Forte, the results were scary. I was absolutely blown away by how loud and clean they could play.

I think you need to quit reading about the LS50’s - that will drive you crazy.

Many of the Marantz amps were under rated.
The KI Ruby on a bench tests closer to 260 watts in 4 ohms. While the PM10 showed over 550 watts in 4 ohms and below.