Laid back DAC under $800?

If your preamp or integrated has some EQ you could dial the treble down a bit.

FLAC > Roon> Raspberry Pi> DAC> Jolida 1501 hybrid amp>Onix RS750 speakers (soon to be updated).

You can do some EQ in roon, that's where I would start. 

@djones51I've been messing with it and don't know what the heck I'm doing. :-)

It varies but the area that most people find tiring is around 4.5khz you might try putting a slight notch there say -1db. Leave the rest alone and try it for a while if it's  a little better but still to much try -1.5 in that same area. Don’t increase anything without adjusting headroom down a few dB.