Liking the answers here so far.
Here's how I would rank it. Things that are important in no particular order:
-Being in a good mood.
-Having a comfy place to sit or lie.
-Headphones. They must have agreeable sound signature/characteristics or one that can be reasonably EQ'd. They must be comfortable and ergonomic. Doesn't matter how good they sound if they feel heavy, insecure, are causing pain, have an annoying cable that gets in the way, etc.
-Parametric EQ. I have yet to try any headphone that didn't absolutely require EQ to be agreeable, and only one that doesn't necessarily need it but still benefits from it.
-Higher bitrate lossy files or greater (lossless).
Things that are not so important in no particular order:
-Amp. Assuming what you already have has enough power for your headphones, and lacks hiss, audible distortion, or any other issues. Even if it did have one of those things, unless it's severe enough it's still not as important. I do however prefer something with low output impedance for the greatest flexibility. Doesn't necessarily sound subjectively better with low impedance headphones, but it's a safer bet. If you ever felt like it you could try changing the sound by adding a resistor adapter to simulate higher output impedance, but you can't really do the opposite.
-DAC. Less ways of sounding different if at all that I'm aware of compared to an amp. Likely about as important as a pair of dingo's kidneys.
-Audiophile jewelry.
Good recording quality can make a big difference, but it doesn't determine what music I listen to or not. Most music I find sounds decent to good anyway. A small percentage sounds flat out terrible, and then some sounds really amazing.