HIFIMAN EF400 R2R DAC / Headphone AMP - I made a review about it, it has tons of driving power, type-c USB input, and both OS and NOS modes : r/headphones
Amazon.com: HIFIMAN EF400 Desktop Balanced Headphone DAC& Amplifier with Himalaya R2R DAC, 3.5/4.4/6.35mm Output for Home Audio : Electronics