Amplifier current vrs watts; why is current more important?


Lately when talking to knowledgeable people in the audio industry I’ve been hearing how current delivery is more important than watts in determining weather an amplifier will drive a speaker.
So what exactly is current and how does it effect speaker performance? How can a amplifier rated at 150 watts into 8 ohms vs one rated at 400 watts into 8 ohms be a better match for a hard to drive speaker?
hiendmmoe
hiendmmoe


Even though the OP’s title is
"Amplifier current vs watts; why is current more important?"

Just to take it off topic as oddio did, with his (excuse me) even grosser misinformation.
To show why output impedance (damping factor) is not the only cause for "tone control" behaviour, but also "available current" is just as if not more important.

Here is a typical case where "current" ability is the factor to making a flatter frequency response, more so than output impedance (damping factor)


Here are two very similar (save for their current ability) amps solid state linear each 60w into 8ohms, but their output impedance (damping factor) is more that 10 x different from each other, these are frequency response measurements (black trace) into exactly the same Kantor simulated speaker loads.
NB: Make sure you see what the graph graduation scale is for both.

1: This Budget Schiit is the one with lowish current , but the "best" lowest output impedance ( best highest Damping Factor) of DF=226 Output impedance=0.03ohm It’s FR is +- 2db
https://www.stereophile.com/images/416Schiitfig01.jpg

2: This Pass Labs one with high current but, worse 10 x higher output impedance and worse 10 x lower damping factor especially in the bass, and yet has far better control over the same simulated speaker load. It’s FR is only +- 0.025db!!!!
https://www.stereophile.com/images/1116Pint60fig01.jpg

As you can see the one, 1: with the "best" lowest output impedance (highest damping factor) is the one behaving like a "tone control" more that the other!!!!!!.
This is because the Schiit is current is limited into the low impedance loads of the simulated Kantor speaker load compared to the Pass labs.

Now back on topic, sorry hiendmmoe

Cheers George

Wow, what a rabbit hole you guys took this poor guy. His question was a simple one, one I try to answer from time to time, but within a couple of responses you guys were into slew rate, and it went down from there, with different people flexing their knowledge muscles. And I know you were trying but like a lot of forum questions it takes very little to take your eye off the ball. I thank you, for you enhanced my general knowledge but I'm not sure anyone answered his question. 
Yes, keep simple!
those 1, 2, 15 W watt amps are useless.

 Get a good amp w minimum 250-300W at 8ohm. Don’t look back, all this nonsense of if 1 watt is great, why have more......??

 Really?
jackalope!

 Power works, these flea watt,  moth,bunny, butterfly  fart amps w 1, to 15 watts amps are a joke.

done mess around.

get a good amp, and don’t look back.
silly stuff.

1 watt, HAHAHAHAH

The sound level of reproduced music is proportional to the voltage. Hence, voltage is most important.; A sagging voltage would ruin the experience.  How much current you need, depends on your speaker’s resistance to AC (a.k.a. impedance) in the audible range. Well-engineered cone loudspeakers like Tannoy, Lowther, Wilson, etc. have a high resistance to AC and require hardly any current to prevent the voltage from sagging. Electrostatic speakers, which have a low resistance to AC require a lot of current to prevent the voltage from sagging.