Should I sell my DAC

If all you're using the Oppo for is the DAC and your budget is around $1000, you could definitely upgrade sound quality.  I have owned Oppo 103, 203, 105D, and HA-1.  I still have the 105D in my bedroom system, but rarely use it.  I use the DAC in my Sony headphone amp in that system, which is much better than the DAC in the Oppo and I have a Bluesound Node 2 streaming into the Sony, giving me a lot more streaming options than the Oppo does.

You might consider using the computer in your office to stream Tidal to a DAC via USB.  Setting up your system this way would give you access to other streaming services like Qobuz, Radio Paradise, etc.

The MHDT Orchid is in your price range, but does not do MQA (neither does the Oppo) if that matters to you.  I've found that it doesn't matter to me, but I know some want MQA.  There are other options in that price range and I'm sure you'll get some other recommendations.

MHDT is a good recommendation. I have a heavily modified Pagoda that does a wonderful job. Before I sold my Node 2i, I compared MQA tracks from it's DAC to the Pagoda. Even though the Pagoda won't do the last MQA unfold, it still sounded better than the Node DAC.

Shakey

Also am thinking of considering R2R DACs. With digital services like Tidal, Qobuz and Amazon HD (I have all three) as means of music for me - I feel the listening fatigue kicks in sooner than I’d like to. Office setup: dedicated laptop for music service web players > Fedilizer > Shunyata USB cable > Intona USB isolator > OPPO 105 usb dac > KEF powered speakers 

The market of dac is the milk cow of company that count of audiophilia neurosis.... There exist excellent dac at low cost....Nos dac…. and the most important and powerful  upgrade cost little and are linked to the :

1-The mechanical environment of each electronic component (vibrations-resonances controls)

2-The electrical grid of the room and of the house

3a-the passive room treatment with materials
3b-the active acoustical space modifications