ESS does sound neutral and is alright.

My 2 cents is that I've used ESS then moved to Denafrips Ares II and it added what you're looking for - more depth and fatigue-free listening.

E.g. compared to Topping, on congested parts of tracks it had just a smidge less resolution, but nowhere near to the point of being sloppy.

I'm not sure if its R2R related, or there's some DSP going on there (supposedly there is), but either way it sounds good and better than ESS.

I would also perhaps explore the DACs with tube output stage that use some older R2R chips. For me the game is less about coloration (I can add more warmth easily by switching input tubes in my amp), more about the depth of the recording.

YMMV the effect a DAC can have depends of course on rest of the chain etc

I recently posted about this in the digital forum, but I was using a Fiio streamer for a bit (with R2r DAC) and switched to a Cambridge MXN10 and found it to be a very worthy upgrade at a relatively little amount of money. Those are streamer combos but both can be purchased as DAC only. The Cambridge uses ESS chips but I noticed a much deeper soundstage and a nicer separation of instrumentation. I also have a Geshelli JNGO3 hooked up to my desktop and I very much enjoy that as well, it's very smooth and detailed. Geshelli is similar to Decware in that it is a small company making things by hand and you can email and ask questions. This is a huge bonus for me.

I agree with some of the comments about DAC + system pairing in that I personally prefer a very transparent DAC and allow the amps/tubes/speakers/headphones to adjust the specifics.  

If I ever upgrade, I might consider Musical Paradise, so that might be worth looking into. There are so many DACs, some very good for very little money, some probably very good for a whole lot of money. Should you want, you could consider taking advantage of the Amazon return policy and order a couple to test out.