A review on HarmonicDyne Helios has been released from headphones.com today as a Fidelio X2 upgrade:

fulla and hel are really good, seriously, if you need mic functionality

I like K371 too, but op should have in mind that it is not exactly a dynamic headphone either.

Great to hear that. How does the sound and soundstage change as you apply Oratory eq? Which eq (default vs oratory) do you prefer with acoustics and classics?

Doesn't Arya respond to EQ well? Try, say, Oratory eq adjustment before making a final decision. Might work.

I usually prefer phone+portable amp/dac to DAPs, but some of high end tube DAP were fairly amazing in their sound quality. But then the question is whether they worth it while you have better sounding tube amps at home.

vote for hip dac too!

I understand your concern. From my knowledge, the three main issues with hifiman QC are: 1. yolk; 2. driver failures; 3. cheaply made other parts (like headbands or pads or cables). From what I experienced directly with Sundara for around 3 months (I don't have it anymore), I felt solid in build...

Sundara has one of the best build quality for the recent Hifiman, and is decent enough even compared to other brands'. In the worst-case scenario, if you are within warranty, they tend to respect that quite well. So, buy new if possible!

1. if your laptop's soundcard is bad for whatever reason like mine (I once spilled coffee over it.. It never got really fully recovered even after this and that fixes), then even a simple $10 USB external soundcard would be a vast improvement. 2. If you expect yourself that you might need a...

for that price, sundara is really hard to beat. Alternatively, hd6xx/600 + 200-300 tube amp would be a nice combo within that price as well.

yes, so does for 58x, although 58x also does get a bit improved with an amp.

when the amp's supply of current is too low to the point that it underdrives the headphones, then yes. Once the amp's power supply reaches to the point that it supplies 'enough' power, the more power doesn't mean much. Instead, how the amp is implemented matters.

i agree that that's the best way

if you want tube, go with vali 2. If you want solid state, anything in between 100-200 would work.

if you didnt find elex to have enough bass, then how about eikon?

hd58x has more similar sound sig with 660 than others, and does not require amp to drive it. HE4xx is also a fine option, but does benefit from amp although not absolutely, at least more than hd58x, and is more different from 660. Other recommendations include Philips' shp9500 and x2.

Elegia is neutral-bright, whereas 6xx is neutral-warm. Elegia has generally pleasant tone (fairly close to Harman target) with upper-mid forward presentation. This adds an extra sense of clarity, and very good for piano, violin, and guitar, but at times female vocals can be too aggressive...