Unfortunately it is not so easy. Some headphones need more amplification than others to reach their full potential, much like speakers. It's very common to see Beyers, Senns, and AKG with pricy amplifiers while you usually see cheaper amplifiers paired with Denons and Grados. The Beyerdynamic T90 I have right now doesn't improve as much as I hoped for with amplification; while on the other hand the Ultrasone PRO2900, Senn HD598, and even my portable AKG K81 sound a bit lackluster on portable/poor amplification. The Senn and Ultrasone were completly unusable with my Fuze while the Beyer worked well with it.
When I first joined into this site I fell into the same trap that many new here do. I got as expensive a pair of headphones I could afford, later added on an amp and DAC. I also bought based on hype alone and ended up with bad mis-matches between headphones and amplification.(due to output impedance and other issues). The right way to go about things would be to think of everything together as a system(or at least the headphone/amp. DAC isn't as important as long as it isn't the weakest link in your system).
In that regard the prices between various headphones become not so important. If you need to spend $200+ on a $300 AKG so that it isn't underpowered are you really saving $200 by buying that headphone over something easy to drive such as a $500 Grado? Is it really wise to stretch your budget for an Ortho or Ultrasone and get an amp later? No. In the few years I've spent here I've done that more times than I'd like to admit. I've spent more time listening to poor sound(due to blowing all my money on a headphone and committing to getting an amp later) than listening to good sound. In the end more often than not I ended up not being able to afford it later on and ended up selling off said headphones for a loss.
It's best if you consider the system as a whole like STAX does.(And it was a good move for them to sell the two together... less bad reviews due to poor amp matching). And you should also have a decent idea of what amplifier you want with the headphones you are looking at. Don't do what I did. After finding out that the Burson 160DS was a bad match for Ultrasones... I bought it anyway.
To keep it short, it sounded awful. Ignore the hype, find what works with your headphones best on a tech level(don't ignore output-impedance!), and make sure you can budget it soon after or with your headphone purchase.
