I made a measurement with RightMark SW, a comparison between Topping D10s-E1DA Cosmos loopback and the same with the Audio Buffer inside the loop.
Frequency response
Noise level
Dynamic range
THD
IMD
Crosstalk
We can see that the Audio Buffer makes no audible degradation. If we explore THD spectrum of individual measurements, then with Audio Buffer inside the loop we have cleaner spectrum with much less high order harmonic distortion components. This because the output stage of the Audio Buffer is able to give much more output current and operates at higher idle current than the output opamp of the D10s DAC.