More expensive DAC the answer?

It's doubtful a DAC change will do much unless the rest of the system & acoustics are sorted out...
 What are your system components upstream?Room size & treated?
What exactly don't you like about the sound?

I have a rather modest system. An Yamaha A-S2100 integrated amp, Klipsch Cornwall III load speakers. The room is a bit odd shaped but 30' x 30' with tray ceilings.
The sound is distortion... and a kinda hollow sound.

Have you thought of trying swapping over the speaker leads on one speaker just in case you have a phase problem.

A single-end triode amp like my Sanei SA-560A (2A3's and Tango transformers) would be a lot better than the SS Yamaha! Those Cornwalls have a sensitivity of 100db/1watt. Most of your listening is at or below 1 watt. SE tube amps are "magic" at the 1 to 7 watt level! Provided of course that the speakers are of high enough sensitivity (Heresy's, Khorns, Cornwall's ...). So changing to another DAC is IMHO not a good idea!