Should I sell my DAC

I have the upgrade itch and am thinking of selling my OPPO 105 player. Currently I am using the player’s fantastic USB dac to play Tidal web player in my office driving powered KEF speakers. No need for Blu ray anymore and don’t use the unit as transport. If I sell the player for $650 - is there a better USB dac than OPPO 105 in the $1100 range? I prefer advice and recommendations from folks that have heard the OPPO USB dac. 
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

Nad m51 dac is awesome . If you can find one . I liked mi e so much i bought another for my other system. 
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I have an Oppo 105 as well and I'm basically using it as my digital hub/transport and send all to an Audio Research DAC8 and couldn't be happier with the ease of use as well as sound quality.