Keep in mind that it's not simple enough to just ask, "what's best?" Audiophilia is like cars, some like coupes, others like luxury sedans, some like BMWs; others like 'vettes.
At any price level there's multiple pieces of equipment at the same level, but with different flavors or style of sound. case in point:
http://www.6moons.com/audioreviews/auralic5/6.html
So basically, decide what style of sound you want, and then you'll have to do your research from there. (It's easy once you zero in on exactly what style of sound you fall into). For example, I like a musical, midrange focused sound and am willing to sacrifice accuracy, so I go for NOS DACs feeding tube amps. (Ofc those are broad categories, and individual equipment can vary in sound tremendously despite being in a particular category, so read them reviews
)
But yeah to reference what someone else already said, a common mistake is to skimp on the source. DO NOT DO THIS. IMO each major part of the chain (DAC, Amp, headphone) can make or break whether or not you think the rig as a whole is enjoyable and worth the money.