You can’t just read a spec sheet though. You need measurements if you’re going the objectivist route and there are definitely objectively bad products at all price points.

I can vouch for this. I used it for years without issues(other than the shitty pot and legs falling off). One thing to note, it fucking oscillates with the stock and most opamp for no reason. Buy the OPA1656 and it will fix the oscillation and temperature issue. The power output is nowhere near that, on a german forum some1 tested it and it was around 600mW into 32 ohms. About powersupplies, any 5V phone brick will provide more than enough power and little noise. To people that said a linear supply “increased the sound”, its bullshit, the U3 have a boost converter inside which is way more noisier than the linear psu. I still use it when i travel since you cannot beat its small size and price,

Remember that different headphones and IEMs may need a lower noise floor or different power characteristics. It’s also worth noting that it’s relatively common for amps to perform worse when the current draw increases.

https://www.youtube.com/watch?v=PqlcJnoIcGo

I have not seen exhaustive measurements of this amp, but it seems to be good for many, but not necessarily all, headphones.

It’s certainly impressive for the price, but as one poster said it doesn’t actually make the stated power into 32ohm. That’s not exactly a shocker for a chi-fi product, but oh well. I used to have a $50 little tube hybrid amp, and it actually sounded pretty decent, if being low on power.

I will say that not all watts (and milliwatts) are created equal either. I had lent my ex a 50wpc class A/B stereo amp I got off of Amazon. It was about $200, is actually quite heavy, large internal caps etc. After a while she bought something to replace it — small, class D, about $75, same stated power output. It sounded nowhere near as good. The difference was immediate and both of us noticed it — and that was two chi fi products against one another.

Would this drive my Grados? I’ll buy it right now.

Hey, this was my first amp, I also got their tube amp. I hate to break it to you but it sounds like dog shit compared to the better amps out there. I like that the style and price are perfect for getting people into the hobby, though.

I wonder if it can run K340s, or be upgraded to do so if not.

To answer question - no. Try buying felicks audio, holo audio bliss, ifi ican, and you’ll understand how better is it.

Also, power isn’t the most important thing

If this headphone amp has a low output impedance near 0 Ohm chances are high that you can drive sensitive headphones and especially multidriver IEMs without altering the bass response. Only issue which might occur is hiss.

Glad that you are happy but better amps are a thing for a reason.

Something like this is a good start but no means end game.