R2R Dac choices.

Many good choices.
I love my Metrum Pavane. I do play it through a tube preamp - Concert Fidelity

If you can afford, the Holo Spring is a cracker, so to the Denafrips Terminator.

Cheers George

There is another major manufacturer, with one of the largest and most capable graduate-level engineering internal staffs in the high end audio world to put very high, if not on top of the list. This 41-year-old, nuclear physicist-run German company is Theory plus Application. They are more casually known as T plus A (T+A). While T+A manufacturers a full line of audio equipment and offers DAC's at several different price levels, they have had a high end version called the MV 3100 HV for a while now. It uses a unique in-house developed, 4-DAC sigma-delta system for PCM up to 32 bit/384, and a separate true 1-bit native processor handling DSD only, up to DSD 512 (8X). Dual power cables, supplies and internal processing chambers completely separate digital from analog processing and a high precision in-house developed SACD transport are included.
T+A just now released a new flagship DAC, the SD 3100 HV and a combination DAC/Preamp called the SDV 3100 HV. Both of these surpass previous designs and set new standards converting PCM at up to 32/764 and native DSD up to 1024. Both the SD and SDV offer an unsurpassed value proposition, priced in the USA at $35k and $37.5k respectively. Both are available now from Lone Star Audio in Lakeway, Texas.

I have I have an Audio Note 3.1 Balanced and enjoy it immensely. Never found anything close to the musicality from others. Although pricey, it's my dac for life, probably.
For lower priced units I did enjoy my MHDT Pagoda quite a bit until it died.

Schiit Modi Multibit DAC. $199 a piece I believe. it is a 16bit R2R DAC. Good enough for casual listening (red book, tidal streaming).  You Oppo203 has a delta-sigma DAC which is very good for DSD. So a 16bit R2R will be a good combination with your Oppo for all listening and watching experience.