Next upgrade to an entry-level system?

Think for money invested vs sound improvement a second sub will do it. Adding another sub really is a game changer. Once you get 2, you will be happy with them for a long time, it's not a short term investment. 

DAC, Cart, cables, are all rotating pieces, while do bring improvements are not the best bang for the buck, or last a long time in your system. 

Speakers are always the best change to sound, but also the most expensive, and take the longest to setup. Sadly once you change speakers, you then want to change everything else to get the speakers to sound how you want them. 

Forget Wharfedale, Mission, etc. Monitor Audio Silver 3Ci will way outperform. Upgrade TT to a Rage P3-24. New or used.

Speakers, amp and sub are fine.

The next definitive upgrade is you get a Wiim ultra streaming dac for around 300 dollars. Play some qobuz official studio masters on it...and compare that back to what happens when you botch a pristine studio master and press it on vinyl.

Currently my system consists of:

AT-LP120 turntable (with the shibata stylus)

A-S301 integrated amp

RP-500M II speakers

RSL 10e subwoofer