Which headphones of Drop's currently available?
I have some rewards points to burn but there's no obviously good options on Drop right now for headphones Contenders Ultrasone - maybe? I don't own any Ultrasones, so curious. Looks like garbage travel headphone which could be useful also. Beyerdynamic DT990 Pro. - Maybe? I have the DT 880 Good price point, really uncomfortable headphones but could be interesting to try the upgraded version. E-MU - strong contender but $400 is a bad price point for what it is. Which of the above would you choose and why? Nothing else on Drop is relevant to my interests, because Already own 6xx 820 800 s Ether cx Garbage / Consumer grade Meze 99 - garbage bass canons, hard pass No gaming headphones obviously Sennheiser wireless - no to wireless/bluetooth Hifiman - I have 2 of drop hifimans and they make really bad cheap shit on Drop, hard pass on HE-R7DX Aeon - I own the closed, Drop refuses to address #padgate so no reason to buy open Beyerdynamic 177x - wireless, nope Too similar 8x / 560s...
Mar 28, 2024
The thing with the DT990 is that it's a pretty bright headphone (beyer spike in full effect), and the 600Ohm version is not going to get all that much warmer even with high output impedance amps (say, 120Ohms). So just buy what looks nice and has enough voltage output.
https://diyaudioheaven.wordpress.com/tutorials/power-impedance-etc/
http://dr.loudness-war.info/
People that think the O2 doesn't have enough power are likely either also confusing gain with power, or they're deaf, or they're confusing placebo with power. Don't get me wrong, placebo is a valid and important source of enjoyment in audio, but it doesn't make the O2 underpowered. In any case, the A30 has about the same power output as the magni 2 uber, and I don't recall anyone saying that was a problem.
Power is a separate issue. It's more about whether the amp is up to the task of providing the output levels you are asking of it. So say the amp has enough gain (eg, your load is an Aeon, which is 14Ohms). Can it also provide enough power to that load with acceptable levels of distortion? Typically this is given as the max power output into a resistive load for a given amount of distortion (for example, 1% THD).
With low-impedance loads, nearly all amps are current-limited, meaning that the voltage will start sagging before it reaches the max output voltage (this is also called soft-clipping). Clipping is one way that a signal can distort, and typically it's the distortion that we care about with power ratings. With SS amps we aren't going to care about low-impedance loads, as their current output limits are quite high. Tubes cannot supply much current, so OTL tube amps sometimes have trouble with low-sensitivity low-impedance cans like the Aeon.
With high-impedance loads, SS amps will be voltage limited, meaning that the amp will hard-clip when the output signal hits the max voltage limits. This is very audible, and not subtle at all. When people complain about an amp not having enough power, this is not what they are hearing. One other thing to point out is that the sensitivity of the headphones are important. The HE-6 has a notoriously low sensitivity (I've seen suggestions it's ~75dB/1mW). The Focal Clear has a sensitivity of 104dB/1mW. As a result, the Clear is a much easier load to drive, and can be more or less adequately driven by cellphones with good output amplifiers. The HE-6 absolutely cannot be driven by any cellphone, period.
Lastly, I didn't mean to suggest that the O2 is equivalent to the A30, it isn't. I'm just pointing out that O2 isn't underpowered, as it is so popular to say these days. 88mW into just about any normal pair of headphones will blow your eardrums out (not the HE-6, but it's in a class of its own). 143mW will do the same, just more so. If the O2 isn't getting loud enough, then the problem is that they don't have enough gain. If it is getting loud enough, but it is distorting heavily, then yes, it is not powerful enough. But in that case, either 1) they are going deaf very quickly, and who cares what they think about audio gear at that point, or 2) their hardware chain is broken somewhere and that's why it's distorting.
Using an amp with 120Ohm output impedance gets you a 1dB bass boost, which isn't very audible. He recommends EQ for fixing the treble/subbass.
Longer answer, in a valid blind test, you will not hear a difference between the two, unless the output impedance of the A30 affects the frequency response of the headphones used. However, the A30 does not have a high enough output impedance to make a difference with the DT990. With, multi-armature IEMs, or something like the Focal Clear, the 1/8" jack would make a difference (1/4" jack probably wouldn't).
Like Solderdude, I don't hear differences between (working) amps. Basically all half-decent amps have a flat frequency response and negligible distortion and noise (this is true even for most tube amps). Frequency response is always going to be the most audible aspect of any piece of gear, which is why headphones and EQ are so important. The main audible differences between amps are output impedance and (a lack of) power output. Large output impedances are easily audible with the right headphones (low impedance, strong resonance in the bass) because it affects the frequency response. Power is only important until you have enough, then it doesn't matter. Not enough power results in clipping, which you can see in the frequency response.
I have not seen anyone a/b different (properly working) amps in blind tests (I have seen marv's "tests" on SBAF, but they aren't well controlled and sample size is way too small to make judgements). Tyll says he can, and I believe him, but 1) he has a lot of training in this regard as the founder of one of the first commercial headphone amp companies, and 2) his descriptions of the differences are exceedingly subtle (eg, amp A makes him want to dance more than amp B). I have never been able to replicate his (unique) technique for performing blind tests, maybe because i don't like to dance.
If the resonance is weak (small peak in impedance), then the effect of using high output impedance is not as pronounced. This is the case with the DT990, which is why even the 250Ohm version is not strongly affected by a 120Ohm output impedance. Foster drivers also have fairly weak resonances. HD6X0 have a stronger resonance, as do the Focals, and they are more responsive to high output impedances. Ortho-dynamic ("planar") headphones are purely resistive (more or less), which means their frequency response is not affected by output impedance.
Also, "impedance matching" is not really a thing at these frequencies/power levels, unless you mean something other than what that phrase normally means in EE.
One last thing regarding "what the designer intended". I remember reading somewhere that 120Ohms is a kind of stardard, and some headphones are designed with this in mind. Consider that Beyerdynamic's own headphone amp has an output impedance of 100Ohms, and the HDV820 is supposedly around 40Ohms. My opinion is that people should use whatever they like best. Garage 1217 has an amp (polaris?) that has variable output impedance (designed by solderdude), so you can pick whatever suits your mood or headphones.