Not sure what went wrong with the pair OP has, or where the incompatibility lies. I'm listening to my pair right now and they are simply very good headphones.

Bass is very it should be for my taste and is not boomy - that would show with the dub techno playing at the moment. Soundstage is not particularly wide, sure, but instrument placement is quite precise. I recently even listened to a full symphony with them, and that is normally where I switch to the HD800. Not the same experience, but very enjoyable nonetheless.

/u/AudiophileHeaven Why do you disable the clipboard for your blog? I just wanted to quote something and got some garbage copyright notice.

Anyway, stopped reading at the claim that system-wide EQ is not possible on Windows.

Glad that I could be of help!

High output impedance on the amp + frequency-dependent headphone impedance leads to changes in the frequency response.

The Clears, like many dynamic headphones, have a strong rise in impedance around the resonance frequency of the driver (~50 Hz here). This leads to an increase in bass around that frequency.

Bullshit on top of nonsense with a healthy dose of idiocy.

Sources, DACs and amps are solved problems as long as you buy stuff made by engineers who use measurements for validating their designs and not by audiophiles with golden ears.

Headphones and speakers are more problematic, especially since there are the headphone + head or speakers + room interaction. Optimizing this interaction makes sense. However, that's not with audiophile tweaks but EQ and, for speakers, room treatment (e.g. absorbers).

What do you consider "serious saving"? If this means eating ramen for months, or otherwise limiting even remotely important things then don't do it. You are enjoying your music and the heavens won't open when using the HD800(s) (I use a HD800, triangulating in regard to the HD560s based on my experience with other headphones that others rate about the same).

Having said that, if you can afford to save without it messing with your life, the HD800 (+ EQ) may well be worth it. There is lots of music where I'm absolutely fine with my work headphones (SHP 9600, because comfort), my out-and-about Galaxy Buds or the trying-out-the-current-low-end Moondrop Chu or Salnotes Zero. But for classical, especially symphonic, music I pretty much always use the best headphones/IEMs available to me and usable in the situation (so most of the time the HD800) because it helps my enjoyment. The technical improvements such as better instrument separation and placement make it easier to understand what is happening and to just get lost in the music.

As I said, there are use cases where you are OK with a low-powered source - and there are ones where you aren't.

For example:

I have a hearing imbalance so I reduce the right channel by 6 dB (quadruples power requirements) and I would run this using oratory1990's EQ settings, which in turn decreases volume by 7 dB. So that is a reduction in max volume to 96 dB.

With music with limited dynamic range 96 dB peak loudness is fine. So when listening to most pop or rock the Apple dongle would still work. But I also like to listen to recordings of symphonies at a level comparable to that in a concert hall. This means that momentary peaks in the music can go up to ~115 dB (average listening volume is much lower). Clearly the Apple dongle cannot provide the power required for this.

The Sundaras have an efficiency of 94 dB/mW, which is on the low side.

For example the AKG K371 (headphone) have an efficiency of 114 dB/mw.

So with the same amount of energy the K371 are four times as loud as the Sundaras (each 10 dB is a doubling of volume).

This also means that to reach 114 dB the Sundara requires >70 times the energy (> 70 mW) required for the K371 (a 3 dB increase in volume requires double the energy).

In practical terms this means while your phone you can drive the K371 for pretty much all music (even very dynamic or quietly recorded one) and in allmost all situations, you will not get usable volume with the Sundara for many use cases. The same may well go for your laptop or tablet headphone out. On these sources dynamically limited pop productions listened to in a quiet environment at a sensible volume may well be fine while with dynamic orchestral recordings listened to with a bit of background noise you will not be able to get things loud enough that you can clearly hear the quieter passages. In this case you need an amp which can provide the additional power.

When considering efficiency and power requirements you shoud also consider EQ. In the case of the Sundara oratory1990's settings for the Sundara have a 7.5 dB reduction in volume (preamp setting to avoid digital distortion due to the 7.5 dB lift in the bass). If you use that EQ (and do not use any EQ with a negative preamp setting for the K371) we are now looking at 27.5 db difference in efficiency. So you need >500 times the energy for the Sundara. For 114 dB, which you may want to reach very temporarily e.g. during recordings of large orchestras, you now need >500 mW, which is more than a lot of dedicated headphone amps deliver.

- Invest your money into headphones/IEMs, not DACs and amps. Most sources are good enough. A cheap-ish DAC/amp combination that has enough power is all you need if your phone cannot power the headphones.

- Frequency response is the primary factor in a good headphone. The Harman curves are a good initial target - you are unlikely to completely hate things tuned like that. Stay away from "esoteric" tunings that "highlight unexpected details in the music". You do not want to hear unexpected details, you want to hear the entire piece. (crinacle's frequency response measurements are a great source)

- EQ is a great way to deal with issues with the frequency response. Cannot fix all problems, but a lot. The AutoEQ project (on GitHub) and oratory1990's manual EQ profiles are your friend. On Android try out wavelet, on Windows use EqualizerAPO, possibly with PeacGUI.

- Comfort is vital. The angels singing into your ears is worth little if you have to pause every 15 minutes because something hurts.

- Good sound does not need to cost much, especially with IEMs. You can get enjoyable IEMS for ~20 UDS.

- Diminishing returns with more expensive headphones are real. Whether they are worth it depends on you - what music you listen to, how you listen, and whether you can easily afford it. Do not ruin yourself financially for marginal gains. (I have a couple of 1k-USD headphones but could live with ones that are a lot cheaper if I had to without thinking that I am missing anything absolutely essential in the music.)

- Cables are a scam. They do not make any audible difference.

Moondrop Chu