what cable should I buy for my system?

Elements of my system:

Source Esoteric K05X

Rotel Michi m8 monoblocks

B&w 802d3 speakers

With a simple high-quality copper cable, the sound is currently neutral, forward, with an unfavorable wind, but mainly with depth and short decays. It’s dynamic, fast, tight, but it lacks sophistication, especially the ideal space mapping and the long, delicate decay of the sounds. I would think about used cables.. Budgeting is obviously important, but I haven’t done it yet, first of all I would be interested in your opinions on which cable brings what and in what price-value ratio.

Thank you very much for your help.