[jmileham]

> It's really cool hearing what they heard in the studio control room for the final mix. And often surprising.

But that's not quite what you're hearing - you're typically hearing what happens after the final mix is shipped to a mastering engineer who listened to the recording on a variety of intentionally flawed sound systems (probably including the "car test" - playing the tune on a car stereo with road noise, which is about as hostile an environment as people will expect to enjoy music in). Then the engineer threaded the needle to come up with the most pleasing sound they could muster for the intended market.

In the process the recording will have been compressed and EQed quite a bit, and likely will sound a good bit richer at a given loudness than it did when the mix was done - you should be able to "hear through" the mix better than before, unless the mastering engineer was simply going for loudness-at-all-costs, in which case, it might just be loud.

Anyway, not to take away from your point - good headphones, or even just headphones with different frequency response than you're used to, will open up different details of a mix, for sure, and flat response will give you the best chance to hear any details that weren't pushed to the fore intentionally, which can indeed be eye-opening.