Interconnect priority

What about Streamer to DAC (assuming they're separates)? Further up the chain, more consequential, perhaps?

DAC to preamp made the most significant difference in my system. What is lost at the source can't be gained further down the line. 

When I used Transparent Audio cables a few years ago, their hierarchy was source to pre most important, then speaker cables, then pre to amp...

Agree with all the above — closer to the source is more important.

Closest to source usually means lowest signal level. That's what matters in analog.