Christof, not sure if you need a "one box" solution for some reason, but in case you do not I will recommend the Maverick Audio TubeMagic D1 USB DAC (and tube pre; w/headphone output) + a Virtue One t-amp. The Maverick DAC is maybe $225 new. You'd have to pick up a used Virtue amp, but as they are starting to deliver second gen products now I would expect to see some originals on the market soon. Certainly should be attainable for $250 max.
This is the C&C set up I am running, so I am obviously biased.
The Decco refurb, in comparison, is much larger that these two pieces combined, and imo not in the same league sonically. I A/B'd the Decco vs the Maverick/Virtue combo.
Lots of other amp options out there as well.
Good luck.