Question about power and AMPS
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Darksoul

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Lately I've been obsessing about headphone amps, after experiencing first hand what some extra power did to the sound of my IEMs on my portable rig. I want to replicate this on my desktop rig.

However, I think I'm lacking some technical knowledge about what all the power spec numbers actually mean for my music and my equipment. I'm not technical illiterate, it's just that I could afford to know a bit more before going on a shopping spree filled with hubris and half truths.

For instance, I read some 400 USD amplifiers that state this on their output specs:

300 mW RMS at 300 Ohms, Single ended
900 mW RMS at 300 Ohms, Balanced.

Whereas I go and find a 500 USD class A amp that simply states:

2.5 W at 16 Ohms

Or a 900 USD amp/dac that goes:

1.8 W per channel at 8 Ohms.

Or a 2.7K USD amp/dac that states:

Output: 7.0 volts balanced

And then a 350 USD Tube amplifier:

Power handling capacity: 1 W.

A 250 USD Class A amp:

250 mW at 300 Ohms RZ (single ended)
1000 mW at 300 Ohms RZ XLR (balanced)

What's going on here? How do I bring all these numbers to a common ground so I can get an accurate comparison between all of them? Am I getting more power at 300 Ohm per each dollar with a 250 USD amp?

This is without even taking into account all the other variables like output impedance, sound signature and other connectivity, headphone efficiency...

Will my music sound "better" with a much more expensive, albeit probably "less powerful" amp, or I just go for the most Watts at 300 Ohms for the lowest cost? Why am I measuring all against power at 300 Ohms? Because that's what my main cans have.

How do I go about reading through all the amp specs out there? And please let's keep it at a numbers level, I know there's also the soundstage, imaging, best pairing and all other poetic yet conceited words we use to describe sound, just POWER!
 
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Zenvota

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I wouldn't focus to much on power ratings, just make sure it has enough for your hesdphones/iems. For me, other things are more important, low output impedance, thd, signal to noise, the volume scheme(relay based woot), the power supply(transformer type etc.).
 
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ProtegeManiac

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What's going on here? How do I bring all these numbers to a common ground so I can get an accurate comparison between all of them?
I wouldn't get too caught up in being able to get a direct comparison since there isn't any. That's like comparing a supercharged 650hp Camaro for $65,000, a Lotus Evora 410 with a supercharged and modified Camry block for $70,000, and a V12 Lamborghini for $650,000. They're all different cars. With headphones at least just check the power output at the impedance of the load you'd put on it and the sensitivity.

It's the same in other hobbies or equipment. Sure you can get a decent kitchen knife for under $70, but if you want a Japanese or German knife, you have to shell out more. And then there's the differences between them (that you can find in some cheaper knives that copy them). Japanese knives tend to be very hard steel that requires less frequent sharpening, but some can't be honed even on a ceramic honing rod because they have a single bevel edge that can get folded over; they're also harder to sharpen; and in some cases they don't have any chromium or molybdenum in the alloy so they have to be kept dry as a bone; and the stiff steel means that while they won't lose the edge quickly, they can chip if used incorrectly; the profile on nearly all but Shun also have a flatter edge, if not nearly or totally straight.


Am I getting more power at 300 Ohm per each dollar with a 250 USD amp?
Very generally, yes, it's easy enough to get more power per dollar at 300ohms than at any other impedance. But that's not just the amps.

First off, provided a decent amp that doesn't trail off voltage output, you don't even need a lot of power since 300ohm headphones tend to have at least 96dB/1mW. 256mW is already enough for those.

Second, in the case of OTL tube amps, these are relatively cheap and provide more than enough power into 300ohms even when running Class A. Problem is that low cost performance comes with a downside - it has progressively lower output at lower impedance, where some reference headphones at that impedance range tend to have lower sensitivity. Going back to the car example, think of an OTL amp like a Honda F20C/F22C or Ferrari engine. You wouldn't use either where torque is important if not preferred, ie, the S2000 is expensive mostly because the F22C can't be used in an Accord nor will it be cost effective if used in a Civic Type R, and you won't see the 3.6L five valve Ferrari V8 as is on a Maserati with more gadgets if not an outright bigger car (Quattroporte), and it got the 4.2L version with stroker con rods and different cam profiles for more torque.


This is without even taking into account all the other variables like output impedance, sound signature and other connectivity, headphone efficiency...
You can't discount headphone efficiency because if the headphone has it high enough then that means you can get away spending on a relatively inexpensive amp with less power.

And nowadays thanks to amps like the Asgard you don't even need to choose between getting a lot of power, getting low distortion, and not spending a lot (for lower sensitivity, lower impedance headphones). There's also the Magni3 if you don't care about Class A.

Also 'sound signature" is mostly a product of compromises in the design - output power, distortion and noise, plus output impedance. Without extensive measurements of each combo this is very difficult to account for on each headphone.


Will my music sound "better" with a much more expensive, albeit probably "less powerful" amp, or I just go for the most Watts at 300 Ohms for the lowest cost?
As long as you have enough power to hit the theoretical 120dB peak target everything else thats left is output impedance, distortion, and noise. Yes it can sound better also but without extensive testing of each amp and headphone combo that's hard to tell from a distance. On top of which, you might have subjective preferences.

Some amps with high output impedance like OTLs coupled with very low noise will make for boosted low end performance while not having noise that gets in the way of what low end is there (at least electronically; ambient noise is dependent on other factors).

Some other amps just make do with very low noise but you still have people, likely dealing with higher ambient noise instead, who feel that an amp with no effect in reshaping the sound and has noise almost below what instruments can measure to be "lacking bass," as with Meiers and the O2. In the case of the O2 the too present top end just makes that worse for some, although personally not really a deal breaker for the price (what is a deal breaker with the O2 is that you can just get a Magni for less).


Why am I measuring all against power at 300 Ohms? Because that's what my main cans have.
If you're sure you won't use anything with less than 250ohms you can just get a Darkvoice DV336se.


How do I go about reading through all the amp specs out there? And please let's keep it at a numbers level, I know there's also the soundstage, imaging, best pairing and all other poetic yet conceited words we use to describe sound, just POWER!
You can't keep the numbers level other than if you're just looking at power per dollar, in which case, get a Magni3. Nothing's gonna beat that.
 
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Darksoul

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Thank you for such an amazing reply, that's the only way to get through my thick skull.

you might have subjective preferences
Yes, I like bling. And am a bit of a snob, so in all honesty on top of power I would like something I can show to my friends and family when they come over: "Look how pretty it is! it's also massively powerful!"

You can't keep the numbers level other than if you're just looking at power per dollar, in which case, get a Magni3. Nothing's gonna beat that.
It's not pretty enough! But yes, I get what you mean, it can't be numbers alone. Back to the internet in search for the prettiest most powerful AMP I can get for less than 1000 USD,
 
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Zenvota

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Yes, I like bling. And am a bit of a snob, so in all honesty on top of power I would like something I can show to my friends and family when they come over: "Look how pretty it is! it's also massively powerful!"

It's not pretty enough!
You're going to have to spend well over $1,000. Even Meier Audio dropped the Shanling chassis used for their $2,000 and up CDPs...


...and are using the plain boxes now.


And Schiit has better looking chassis than AudioGD. If Schiit is already ugly to you then AudioGD will be worse.


But yes, I get what you mean, it can't be numbers alone. Back to the internet in search for the prettiest most powerful AMP I can get for less than 1000 USD,
Maybe get the WooAudio WA6SE if you want something pretty and ca be sure it can drive pretty much anything but electrostats.
 
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