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KEF LS50 Metas paired with Marantz PM7000 (not PM7000N)?

Will this pairing work well enough? I’m interested in purchasing a set of the new KEF LS50 Metas for my study. Marantz states for this amp (95W per channel) not to go with speakers with nominal impedances below 8ohms. I’ve heard tell that even though KEF states 8ohms for the LS50 Metas, that they are more like 4ohms in their demand. I had used the PM7000 on my Vienna Acoustics Beethoven Baby Grands, and the amp didn’t quite do the job. The speakers never demanded so much from the Marantz that the protection circuitry had to kick in, but there was something noticeable in the sound. I also think that I may have clipped one of the midrange drivers with this pairing, but the damage to that driver may have just been coincidental. I eventually bought a Peachtree Nova 300 for the Baby Grands, and that pairing sounds great. Anyway, I digress. Back to the LS50 Metas. Any potential damage with this pairing and will I get nice sound in my fairly small (~9’x10’) study? Thanks.
jwhite
mastering92
870 posts
 
Nominal impedance matching is important when pairing amps to speakers. As you mentioned, there can be fluctuations in the impedance as the speaker is playing.

To provide some perspective, in my very early audio days I used a 4 ohm speaker with a receiver that was rated at 8 ohms and up. The receiver would play - then clip - and eventually shut off by itself. I have owned power amps in the past that were rated at 4 - 16 ohms. I could pair anything with them and never have a problem.

Impedance is a measure of electrical resistance. A well-designed amplifier would be able to handle drops and peaks.

Check out - Emotiva BasX A-100. Really amazing value for the money.

turnbowm
353 posts
 
"....Marantz states for this amp (95W per channel) not to go with speakers with nominal impedances below 8ohms...."

I would heed Marantz's advice. The impedance of the LS50 Metas is not quite as bad (low) as your Baby Grands but it's close. I personally would not use any amp/integrated that's not speced for 4 ohms in this application. Damage to speaker drivers may result when amps are driven into clipping.
jwhite OP
18 posts
 
Thanks to all who responded so far. I emailed KEF with this concern, and this was their reply:

"The Marantz you are looking into would be a good pairing. We list the LS50 META as an 8 ohm speaker because the system has an 8 ohm impedance. This will not affect the Marantz even when the impedance may drop down under load.

The high end of the power range we recommend is 100WPC into 8 ohms. Since the Marantz will cover 95% of this it will be a good match."

The Metas arrive tomorrow. My plan is to stick with the PM7000 and see how it goes. There probably won't be much of a need to crank up the volume so much as to damage the speakers or amp as I'll be using these in my fairly small study.

Of course the main caveat here is that KEF's main interest is in selling me speakers.
turnbowm
353 posts
 
@jwhite - The Stereophile review of the Kef LS50 Meta may be of some interest to you. In the Measurements section, the reviewer stated  "The partnering amplifier needs to be comfortable driving 4 ohms."

https://www.stereophile.com/content/kef-ls50-meta-loudspeaker

FWIW, I have owned a pair of the original LS50 for five years and can attest to their current-hungry nature. Good luck with your Metas.
jwhite OP
18 posts
 
@turnbowm - The Metas arrived on Monday. I've been driving them with the PM7000 with no obvious problems. The sound is great; however, there might be room for improvement with a better amp. I did not notice much of a difference when I compared the Metas hooked up to my Peachtree Nova 300. I'm about to purchase a REL T/7i subwoofer to join them.
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