What are the odds......

"...I thought I'd reached the limit of what I could get out of mine. Then I tried a set of $35 springs under the turntable. Never saw it coming..."

I think that is what makes an audiophile, the willingness to try new things and make changes to improve your system. You don't know what changes will do until you try. they can often be dead ends but even then you have learned something.

It is very easy to improve what is already good. But at some point, where you are very high, it does become more difficult. In the end it is the recording and the room. 
How to improve the source if you have Continuum table, as an example ?
Well, good master tape dubs, of course, and real good R2R deck.

i have a lot of equipment (several pairs of speakers and the ancillaries to drive them well) - i find i enjoy a variety in presentation, so sometimes i swap them in and out over periods of time ... harbeths have a lovely tone, warmth and thickness that is very comforting... proacs have a precision and clarity and spotlit sharpness that makes the music more exciting, quad esl’s have a purity and hear-thru quality that is very appealing very refined ... and so on... the new spatials have bass slam and openness that is very appealing, especially after listening to the quad esl’s after a while!

each set of components needs optimization, in terms of placement, room interaction, equipment, cables, what have you

hard to say which is better... all very good just different presentations with different strengths and weakness that are highlighted in different types of listening and musical genres

If its good from begining it will get better with time. Know the limitations, financial, system, space, music, and proceed with experimentation and caution. What matters is the involvement with a wide range of music and not a particular style. The mastery is to create something impressive on paper to real music making. Patience will be rewarded. And i am pretty sure, having the same amp/pre/speakers, that i know more today than did nearly 20 years ago or even yesterday. Yes the odds are good.

G

I think it comes down to cost vs performance. I love the sound of my system now I am sure it could be improved but at what cost? Likely too much for me to consider upgrading as my performance level, to me, is quite high.