Interconnects

IMO: Auditioning cables is not one of the great pleasures of life.
In fact, it can consume way more time than it’s worth. ;^)

The best cables for more applications in the world are van den Hul. They have 63 pages of Audio cables. They supply cabling to 38 equipment manufacters including B&W Focal SME to name a few. van den Hul has been in the cable business since 1980

RCA cables can only ever equal or be second best to XLR. RCA connectors were developed as a low cost solution for phonographs which is why they are often still called phono jacks. They are perfectly adequate if you simply need to connect a TT, however they are a bit of a compromise for other active audio equipment that run on line level signals. You really should consider equipment that has XLR connectors if you are prepared to spend that kind of money on cables.

Many of the problems with RCA interconnects come from inevitable minuscule grounding differences between various powered components. Balanced XLR seeks to eliminate or minimize these inevitable problems from connecting two devices running off their own separate power supplies. XLR also has better shielding and immunity to RF/EM.

If you invest in quality balanced components with XLR interconnects then you are always in advantageous position compared to RCA. RCA might equal XLR in a perfect world with no slight grounding differences in the different components you have chosen (this is luck) or RF/EM issues (again luck).

In the audiophile world you may connect TT, Phono Amp, pre-Amp, power amp which is 4 devices and already there is a reasonable chance of a problem. In the pro world a lot more equipment gets connected and the probability of an issue is even higher. Pro has remained using XLR while consumer audio uses the cheaper solution of RCA.

Audiophile equipment manufacturers that offer XLR in addition to RCA are providing you a trouble free route to connecting a variety of high quality equipment from other manufacturers. This allows you choose equipment that is best for you and the sound you seek rather than trial and error of finding gear that connects well together.

Note that as equipmemt ages you may also develop ground differences between equipment that may have worked fine with RCA in the past - so balanced XLR also helps ensure interconnect troubles are kept to a minimum even as equipmemt ages.

$500 and something really good.  Hmm.  Good luck with that or try to buy used, but even that option will leave you with old generation.  There have been so many significant advancements with cables.  You have a great system why downgrade it.  I think you should reconsider the budget.

A year ago I tried several different interconnects, I landed on the SR Atmosphere Level 4.  They're the bomb.  Exepensive but they perform well above their price point.

Good luck with the hunt.