I guess the title says it? Personally speaking I don't know how good it can sound and even then am I "colouring" the sound to lean towards my personal psychoacoustic preferences rather than moving towards what was recorded? How do you get a reference for best in your listening room and inside your own head?
I don't think you can ever really know. But...
My approach has been to wander into any and every high-fi/home theater store I come across during travels all over the country (schedule permitting). And as others suggested, see about a visit to a highly/regarded and we'll engineered studio (or two, or three). Visit audio shows.
Take note of the good and not so good in every system (timbre, clarity, dynamics or liveliness, spaciousness, bass response, etc., etc.). And as others suggested, make sure you're using high quality source material.
And then follow the science for the gear you select and how you setup and treat your room (particularly if it's a dedicated space).
If you do it right, you'll still never know if it could sound better, but it will sound so good you'll stop caring.
Something I've noticed as my equipment improved and my listening space and system setup improved is that I enjoy a wider and wider variety of music, and tracks with nuance and ambiance became more enjoyable. And yeah, I can hear the deficiencies in mediocre tracks as well.
Unless you hire a respected expert to design a dedicated room and select top-tier performing (not necessarily top-tier cost) gear on day one, it will be a journey. Note what traits are most enjoyable for you, and keep an open mind.