Do we need powerful amplifiers at low volume?

[ClementNerma]

Hi there!

I have a (kinda stupid) question. I'm a beginner in the audio world and was wondering why we couldn't, for instance, drive a pair of KEF LS50 (known to be power-hungry, but rated at 25 - 100 W RMS) with a small amplifier like the AUDIOPHONICS BT60W PRO (which is a $50, 2x55 W amplifier).

What's the point of a higher-end amplifier? If we put aside the "sound quality" itself (with higher quality components), do power actually matter as long as you're not listening at high volume?

Wouldn't technically a 2x5W amplifier be enough to drive a pair of KEF LS50 if you listen at really low volume?

Thanks in advance for your help

 

[Ricwa]

Depends on what you mean by really low in the case of 2x5W but you’ll be fine with 2x55W.

 

[kekus]

You can use this tool to calculate SPL output based on amp power: http://myhometheater.homestead.com/splcalculator.html
Then you can use any SPL measurement app on your phone, at your listening position, to see how loud that is for you.

 

[solderdude]

Wouldn't technically a 2x5W amplifier be enough to drive a pair of KEF LS50 if you listen at really low volume?

yes.
That said.... 25W to 100W amps also will work well.

 

[ClementNerma]

Depends on what you mean by really low in the case of 2x5W but you’ll be fine with 2x55W.

Thanks, when why do we say the KEF LS50 are power hungry and most people recommend expensive amplifiers for them? If 2X55W are enough, there are plenty of cheap options out there. Or is it because affordable amplifiers don't have high-enough quality components to make the LS50 shine?

 

[boxerfan88]

Look at it another way… it’s the quality of the first watt…

 

[solderdude]

yep... nonsense... quality is important for the entire voltage (power) range.
The first few Watts are the easiest.

 

[VMAT4]

It would be best to trust the manufacturer's minimum power rating. The sensitivity of the speaker and its impedance curve come into play as well.

 

[kekus]

This is from Amir's review here on ASR, explains why they are hard to drive:

 

[ClementNerma]

It would be best to trust the manufacturer's minimum power rating. The sensitivity of the speaker and its impedance curve come into play as well.

Ok so given the manufacturer rates the speakers for 25-100W, would there be a real audible difference between a "cheap" (but e.g. well-reviewed on this site) $100 amplifier and a $10000 one?
I'm really beginning in there so it's kind of complicated given many people seem to have opposite opinions on that matter ^^"

 

[ClementNerma]

This is from Amir's review here on ASR, explains why they are hard to drive:


View attachment 293417

Thanks!
By "beefy" do you mean high-wattage, high-impedance, or both? Technically if I have say a 2x25W amplifier wouldn't that be as great as a 2x100W if I listen at low volumes?

 

[kekus]

If you listen at low volumes, 25W could be fine, but you need to see how it handles low impedance (4 ohm) speakers, as it takes more current from the amp. You can find good quality cheap class D amps with not much Wattage but that can still handle 4 ohms.

 

[ClementNerma]

If you listen at low volumes, 25W could be fine, but you need to see how it handles low impedance (4 ohm) speakers, as it takes more current from the amp. You can find good quality cheap class D amps with not much Wattage but that can still handle 4 ohms.

I see, so that means wattage isn't everything right? Output impedance matters as well?
Are there any other important specifications I should be aware of when looking at an amplifier's specs sheet?

 

[Sokel]

Ok so given the manufacturer rates the speakers for 25-100W, would there be a real audible difference between a "cheap" (but e.g. well-reviewed on this site) $100 amplifier and a $10000 one?
I'm really beginning in there so it's kind of complicated given many people seem to have opposite opinions on that matter ^^"

No matter what the price is make sure first that the amp has any protection possible in place and it's reliability record.
It's a pity if an amp fails to take speakers in his grave.

 

[kekus]

I see, so that means wattage isn't everything right? Output impedance matters as well?
Are there any other important specifications I should be aware of when looking at an amplifier's specs sheet?

Yes watts can give you volume and headroom for loud and bass heavy parts of music, but the quality isn't in the watts. I would suggest you browse the Stereo And Multichannel Amplifier Reviews section, look for reviews with load variance charts, usually Amir comments on load handling. I would trust those more than anything in the amp spec sheet

 

[ClementNerma]

I see, thank you all for your answers, it's a bit more clear for me know

 

[solderdude]

I see, so that means wattage isn't everything right? Output impedance matters as well?
Are there any other important specifications I should be aware of when looking at an amplifier's specs sheet?

Just make sure the amp can drive 4ohm loads.
Anything between 25W and 250W will be fine.
The higher the Wattage the louder it can play and/or the bigger the room can be.
When it is only used nearfield, in small rooms and never played even moderately loud a lowish output power is enough.
For bigger rooms and/or occasionally wanting to play loud; go for higher powered amps (100W +)

 

[ClementNerma]

Just make sure the amp can drive 4ohm loads.
Anything between 25W and 250W will be fine.
The higher the Wattage the louder it can play and/or the bigger the room can be.
When it is only used nearfield, in small rooms and never played even moderately loud a lowish output power is enough.
For bigger rooms and/or occasionally wanting to play loud; go for higher powered amps (100W +)

Thanks. You say up to 250W but the manufacturer ranges the speakers for 25-100W. Wouldn't >100W damage the speakers?

 

[Sokel]

And make sure that the advertised power is NOT at 10% THD+N,there is a trend amongst companies to do this,better search reliable sources of info,like Amir's reviews,etc.

 

[ClementNerma]

And make sure that the advertised power is NOT at 10% THD+N,there is a trend amongst comanies to do this,better search reliable sources of info,like Amir's reviews,etc.

I always look for reviews anyway, for two reasons: the first one is while the spec sheets is nice to know if the product will go well with the speakers / headphones I have, I want to make sure it actually sounds good, and the second is to ensure it hasn't some e.g. manufacturing or electrical issues.