Happy New Year!
It's up to 300ohm so i would need also something more for higher impedance headphones
Ah, one of the legends of DIY audio, came out of nothing, designed this and helped design some other products, before vanishing again.....
Search for TPA6120A2 on Ebay.It's actually a DSL modem line driver (aka THS6012) that can put 400mA into 25 ohms at 140 MHz with a slew rate of 1300 V/us. So it should be able to drive some phones!
Actually it's powerful enough that you could just wire up 4+ jacks in parallel.Although I have no experience with any of the Ebay stuff with that chip. Actually because the chip is so fast, if the layout isn't exactly right, it can be unstable. And it must be driven from a low offset source which means hybrid buffer. So be careful about anything that looks a little too cheap. It has to be done right or it won't matter how good the chip is. If you do buy something from Ebay, check the offsets with a dummy load first.
Long winded, verbose ... but authoritative and refreshingly different on OPAs from Self & Cordell.He shows 2xNJM4556 in parallel as a voltage follower is difficult, if not impossible to fault. My take is that 1 off is pretty good too and even 1 off with a bit of gain ... as is used by most prosumer (& pro) headphone sockets.Note his emphasis on layout/grounding/decoupling .. all VITAL to good performance and misunderstood by most.My first thought was to find a cheapo 2 stage eBay special and replace the OPAs with his recommendations ... but you can't tell good layout/grounding/decoupling from a couple of pics. He's got a couple of 'recommended' commercial amps though.