Some vintage gear make good headphone amps. I frequently listen through headphones using Marantz 22xx receivers, and at this moment am listening via a 1060 amp. Can't complain!
As with Phono stages, they used to use pretty good circuitry in some of the vintage gear, better than what you generally find today. The 1/4" jacks they used to use are inherently better than the modern mini-plugs, too, because of larger contact area. That said, not all vintage gear is equal in this regard; as ponderbear said, it's all over the map. In general, though, vintage tends to be better than new, PROVIDED the headphone jacks are in good shape and cleaned/DeOxited. I've found a number of headphone jacks in old gear to be pretty heavily oxidized, probably because the owner didn't use the jack, and over the years simple atmospheric exposure took its toll. Sometimes they have been loosened or damaged, probably from people bumping plugged-in headphone plug-ends.
Not to divert the thread, but I was thinking earlier today when plugging in my headphones, about the whole subject of headphone jacks. We pay a lot of attention to gold-plated RCA jacks, and there are fancy "audiophile' fuses and fuse holders, too ... but how much attention is paid to that headphone jack INSIDE, behind the faceplate? I'm wondering if one couldn't get/design/make a better-quality one, with gold plating, slightly larger and curved contact area, sturdy spring pressure, etc.... Would it make much difference? I don't know, but it may be a weak spot in some gear. I have noticed that the metal in the older vintage jacks is heavier than the flimsy, more easily-bent stuff used in many modern ones. Just another area where the cost-cutting bean counters have had their influence, making gear engineered to meet minimum standards rather than being over-engineered for longevity.
