Your sure bet to get the best sound quality / performance that you will prefer is to post a thread with your budget, your model of cans, your uses for the cans like gaming, movies, and types of music you listen to, your preference for a portable amp or amp/DAC, and then choose wisely. Otherwise, if buying vintage, your best bet would be to try out the amp with your headphones before buying, and that could be tough or impossible to do. If buying vintage, remember you will be dealing with analog connections.
I bought 2 different highly regarded vintage Marantz integrated amps on eBay and neither one drove my Sennheiser HD580 or HD650 as well as my HotUSB1 Amp/DAC that I bought recently for under $100. These vintage amps did drive my cans far louder than needed, which my HotUSB1 does not do. My vintage amps did drive my bookshelf speakers quite nicely though, in a pleasing and warm sounding way, but not nearly as well or as clean as my Panasonic XR55 digital receiver did.
Here were my concerns with my vintage amps. I had no way of knowing how long either were going to continue working since they had about 30 years on them, but neither broke down for the short time I had them. I did not know if the parts were original or had been replaced with something inferior. I did not want to learn how to tell for myself if the parts were original, just no interest in opening them up. I took the better sounding amp of the two to a local vintage audio shop for servicing, but I had no way of knowing if they replaced any original parts with something inferior. However, the shop owner did tell me its parts were original. If buying vintage again, I definitely would buy only after trying my headphones in the store, and only while comparing to a decent portable amp.
I am not suggesting vintage amps cannot be enjoyed, or that vintage amps or portable amps have better sound quality than the other. That's simply a matter of preference. You may find a vintage amp that you would prefer its sound to a portable amp, but then again you may not. Again, your best bet for sound quality / performance, and the sound quality that you will prefer is with a portable amp or amp/DAC.