I strongly encourage you to optimize the system you currently have before you consider replacing any of your major components. I would do the following, in this order:
1. Boot the equalizer
2. Optimize speaker placement and listening position.
3. If your budget and home allow, room tx is important. This can be done physically or electronically. The cost of manufactured room treatments, physical and electronic, can be prohibitive; but, if you’re handy, you can build some yourself using designs available online.
4. Isolate components. In my experience, you can get a lot of benefit without spending very much $. Vibrapods and Vibrapod cones are inexpensive and reasonably effective. If you can afford a slightly higher price tag, I’ve had good results with Isoacoustics feet and platforms. I use Herbie’s grunge buster between components stand frames and shelves to good effect.
5. Don’t accept anyone’s views on power conditioning and cabling, not even mine. The value of these elements in your system is an empirical question, and so one you can answer for yourself. Experiment with them! As others have said, exploration of the effects of these kinds of tweaks is one of the joys of the hobby. When I was exploring these elements of my system, I bought and sold used cables until I found the ones I preferred. I usually recovered my investment when I resold the cables, so experimentation cost me almost nothing. You also can borrow cables from places like the cable company or purchase from dealers who have accommodating return policies. Anyway you choose to do it, I encourage you to explore both power and interconnect cabling. I would begin with power cables and a power conditioner.
6. Once you are happy with the isolation of your components and the performance of your cabling, you are ready to ask the question: what are the weaknesses of my system, and which components should I consider replacing. I would not ask this question until I’ve done the things listed above.
Good luck and have fun.