Good economical used DAC to hunt down

I would take a look at the Cambridge dac magic products. Their stuff is generally good sounding and reliable. No need to buy someone else’s headache. At a few hundred dollars, your choices are somewhat limited IMO. I just did a quick search in the for sale section and there are a number of nice-looking used DACs for under $500.  

what do you mean by a few hundred dollars? See my ad in Audio Asylum for a Audio Alchemy DDP-1

Not sure you necessarily need to resort to an older or used DAC.  A new Topping E30 DAC with separate P50 power supply would be less than $300 and give you great sound.  Best of luck.