"the only physical difference was an additional piece of foam inside the cheaper HD555 headphones, blocking about 50% of the outside-facing vents"

They are likely still making a good profit on the $200.00 "cheaper" pair - just goes to show what a rip-off the $350.00"premium" level of equipment is. Sennheiser should be embarrassed. I hope buyers take notice and send their money elsewhere.

> I hope buyers take notice and send their money elsewhere.

I'm currently in the market for both in-ears and over-ears. Was looking into HD 25 model for over-ears. What other brands are worth looking into? KEF? Focal? Meze?

I personally like Beyerdynamic.

MX 150/100 if you want to have a mic, DT990 Pro if you want open-back and DT770 Pro for closed-back.

Worth mentioning that they're studio headphones, so if you like headphones with a lot of bass you might have to consider other models.

At home I use Sennheiser Game One, before they were rebranded to EPOS. I really, really love them so if you can find them second-hand, go for them. They're hooked up to a Sennheiser GSX 1000. I use this setup for almost three years now and I'm really happy.

For in-ears I use Marshall Mode EQs, I'm on the third pair now and am also really happy. They've got a lot of bass but when I'm commuting I actually prefer it over "true" sound :)

As always with headphones, YMMV. I care about good sound but I'm not that much of an audiophile to care about exact frequency curves etc.

I'm partly having a go at them because I have a pair lying around that broke in less than a year. I usually go through a pair in a year (a year and a half) as I'm not very careful with the way I take care of my heaphones/in-ears. However, having said that, I think the EQs have a pretty mediocre build quality. For example, with the way I handled them, the cover of one in ear piece, fell of after a couple of months, and 6-8 months in the jack connector wires got a bit too much wear and tear and no longer connect properly. Also their EQ toggle made the treble (for the Electronic/DnB/Metal music I listen to) a bit too harsh.

Personally for earbuds/earphones I'd recommend anything which is as flat as possible and then you can boost up your preferred range. Alternatively you can go with a pair that has a measured profile (https://github.com/jaakkopasanen/AutoEq), which you can use to normalizes the frequency response and tweak it after.

For example I went with the cheap AKG Type-C earbuds, which have very harsh mids towards treble (https://www.rtings.com/headphones/reviews/samsung/akg-type-c), but because their sound profile is within the database linked above, I could use Wavelet on Android to compensate for it (and EasyEffects on the desktop) to have them be as neutral as possible, and then boost on top of that. For a ~$10'ish pair of earbuds I am quite impressed. I also had to chose them because I have a "modern" phone that decided that a Jack is so 20th century.