Features and, in the case of some types of DAC, colouration of the sound in potentially pleasing ways.

Big whoop... As far as I'm concerned, youtubers are the prime audience when it comes to premium unboxing experiences.

Kinda, yes. It's hearsay, but it's probably due to power noise. Sadly, the D10 can't take a dedicated power supply. You could try using one of those USB filter adapter things.

The D10 isn't broken, so you could sell it and get a DAC that comes with a PSU. The JDS Atom DAC would be my choice.

I think I'd go for a 7hz Zero or Truthear Hola in order to get a fairly neutral tuning.

Cool! And if you hear any scratching noises in the future then you know that you have a loose hair touching the driver.

The filters have a reputation for making things sound a bit blunted. That bothers some people more then others. It's fine to leave them in but it's good to try without too. :)

I'd take the tuning filters out. Stuff in front of the drivers is rarely a good idea. EQ is a much better solution if you want to knock down the treble.

Getting a balanced cable wouldn't be a bad idea.

The mobo should be fine, but try both.

One month is not unexpected.

It will probably be fine. I would only expect problems if it's used with exceptionally crappy laptops.

I suggest just starting with the WaveXLR. It will be fine.

I'd burn the tubes in first. Plug in the headphones and play a variety of music slightly above your regual listening volume. Do that for a day or so.

I'm pretty sure it will be fine. You can grab a JDS Atom amp if you're worried.

Yup. Should be fine.

You'll hear a helluva lot more treble, that's for sure. It's not really how headphones are "supposed" to sound but more power to you if you like it.

For future reference.

https://www.headphonesty.com/2019/04/headphone-impedance-demystified/

Depends on your wallet and patience.

It's a low efficiency headphone. It might not be loud enough or distort when used with some lower quality source gear.

Better sound quality, worse QC, and moderately power demanding.

The DT700 doesn't have a lot of strong competitors. The AKG K371 and Shure SRH840 aren't as well built. I might consider the Sennheiser HD560s a value contender to the DT900. Although, if you have a larger head, the DT900 might be better overall.

This video might be helpful.

https://m.youtube.com/watch?v=Xq7pnOFbhYs

You want speakers? r/audiophile is a better place to ask about that.

The DT880 also has a treble peak. It's not as bad, but still present.

If your head isn't on the big side then the Sennheiser HD560s could be worth a look.

I suggest contacting the Fiio support.

Almost all DACs and amps in this price range are almost perfectly transparent to the source. You don't really have to worry about optimising or synergy. A K5 Pro would do the job quite well. I like the JDS Atom stuff, but it will be more expensive due to import charges.

Also, I'd go for the HD600 if given a choice. It's very similar but has a tiny bit more treble clarity.

Balanced amps aren't inherently better than single-ended ones, but if a device has both, you should try to use the balanced one.