I don't agree that the sound the engineer heard was the one that was intended. The engineer only has the materials he is given, played back on equipment that is just as flawed as everyone else's. He, too, has biases and preconceptions like audiophiles. He can tweak this or that within limits, but at the end of the day he is just committing the outputs of several microphones to 'tape' based on a few rules of thumb. Luckily, microphones are pretty neutral and humans are pretty good at accepting every mix as 'valid'. Even if he couldn't hear the mix but adjusted the levels by viewing the VU meters, it would probably sound like music.
The audiophile with a better system in a real room may well hear a better version than the engineer - perhaps even closer to the one the engineer had in his head. Simply put, if I record something with my phone, it will sound better when I play it back over a good audio system than when I 'engineered' the recording as I "intended" by listening to it played back over the phone speaker.
Yes, what he heard is what he intended and is what you got.
Well, let me tell you from actual experience how things are done. My son owned a recording studio for a little over two years. Here is what they did. They mic'ed instruments and vocalists, and played the mic feeds to their own tracks on digital tape. Then they played back each track and adjusted the hell out of it to make it sound the way the wanted, to make it sound more realistic over speakers. Then they mixed them together to form the song, then, after that, they did the mastering to make it sound better as a cohesive unit, again using a lot of technology, to tweak again so it sounded how they liked it on their system. That then became the master file. They figure they know better than you do, so you get their best guess at what they figured the song should sound like.
No, you will never hear what he heard or intended unless you are sitting in his seat. And no, the gear is not cheap, its pro gear, speakers and headphones designed to reveal a accurately as possible what is being presented to them, but yes, when you play back what he intended on your system, it may or may not sound better than it did in the studio, it will not be the same though, and that is one of the points I was making, an accurate system will do as little change to the signal other than increasing its power, therefore revealing the
Differences between recordings, while anything less than accurate will paint things with its own brush, none will however be what he heard, and what he did everything in his power to sound the way he wanted it to sound.
Mastering, although attempting to play to the going trends, such as high compression, never the less, is still done at the studio, with their system and their idea of what it should sound like, and you will often find that mastering studios are not living rooms, and they have one or two sets of speakers of their choice, hardly a sampling of all the different speakers or rooms where we actually play their "best guess".