Cost break down of hifi system

Room, speakers, network dac, amp, power cables, interconnects.

The better your system is, the more you will need to spend on quality cables to get the best sq you can out of it. If you can’t hear the difference between cables, then what are you doing in this hobby?

Also, if you are building a system for digital streaming, get a good network dac, you can eliminate the preamp and streamer. My network dac is directly connected to my amp (sold my McIntosh preamp and phono preamp when I sold all my analog gear) and my dac is a Roon endpoint. Got rid of my Auralic music server a few years ago.

1) The room

2) Speaker and speaker placement

3) Power

4) IC's

5) Components

The OP is kind “already invested” in the speakers and amp.

I would probably #2 ahead of #1, but that also opens up room correction amps and active speakers.
Active speakers do cut out a large portion of #3, #4, and #5… but that is a bit late now.

I think of cables/interconnects as a more-or-less fixed cost, not as a percentage of the total system cost.  Blue Jeans Cables sells  Canare 4S11 speaker cables, terminated with locking bananas, for $5.90/foot. This might be 10% of a starter system, or less than 1% of your end game system.  

If you think you can hear a difference between the Canare 4S11 and something many times more expensive, well, maybe you can. I suspect all you're really hearing is a difference in gain resulting from a change in length, gauge, or termination quality,  Granted, a system may sound better (not just louder) at higher volumes. Usually, there's an app (or a knob) for that. 

Put most of your money into the speakers! Audio electronics have been transparent to the source for several decades. Paying more just gets you more bling - no real sonic improvements. I suggest getting a pair of Genelec active monitors and ditching the amp. Expensive yes - but you could spend that much just on an amp and have nowhere near the sonic quality of the Genelec's!

Given that you have speakers and amplification. The next step is to decide on the source components. What media will you be using?

I would then get some budget cables and set the system up. Run it for awhile and get to know it. Adjustments inroom treatment, cables, and power (in that order) can be made therafter.