DAC recommendation for DSD input

Hello-- 80% of my listening is streaming local DSD (64-256) files via Roon. My current system is Roon Core on an iMac Pro making its way to a Sonore Optical Rendu which is connected, via USB to the DAC in my Hegel H390 integrated which feeds Magico A3 speakers and a pair of REL S/510 subs.. There is nothing at all objectionable to my current system, nonetheless, I am wondering if an external DAC might be an improvement over the H390's DAC and if that is a worthwhile spend.  I am space constrained so I must stick with an integrated (pre+amp), but do have space for a DAC and the Rendu system.

I have spent hours researching many of the newer and older DACS, including the cheaper "Chifi" DACS (Topping, Gustard R26 and X26iii),  T+A 200 DAC, PS Audio Direct Stream MKi2 and Mola Mola Tambaqui (used) and other DACs in-between (Denefrips Pontus and Terminator, Holo May, Wyred for Sound 10th anniversary, etc).  

I would rather spend $5k-$10K for a significant improvement as opposed to  $1K-$4K for no or a slight improvement. My hope is for more resolution, more musicality, less high frequency fatigue, tighter bass.  Is it unrealistic to expect that an external DAC will bring a significant improvement?

My system is in a decent room, but there is little to no choice in speaker placement or room treatment opportunities.

I have a chance to audition the T+A 200 DAC and the Direct Stream MK2.  In a previous system, I had an MSB Discrete stack which was nice, but I'm not sure that would be the worth the cost today.

What type of DAC (chip based, FPGA, R2R, OS/NOS) is more structured to DSD input?  I've almost ruled out R2R, but could be mistaken?  The deeper I look, the more confused I get.  

Thanks for any recommendations or advice.