So I am searching for a compact USB DAC to pair with a Dell Wyse 3040. Does not have to be excellent but it has to be cheap 
Topping E30 came to my mind but I think is over the top for what I want it. (the wyse 3040 will keep me company in my office so not much to ask for)
If you only want a USB DAC and no preamp, headphone output etc, the Topping D10s is cheap and great. 110 euros/dollars.
Also a reasonable Low-budget DAC:
These are surprisingly good for a second (shed/workshop/office/basement) system, and can be modded to perform even better:
Or alternatively (I haven’t tried this particular one) but it’s worth a punt at the price:
SMSL M2 - USB DAC - Digital SPDIF Optical Out and analog audio out jack 3.5 mm