What DAC are you using?
How is it connected to the digital source?
What cables are you using, i.e. interconnect and power.
I stream from my iMac, using a good USB cable, into a musical fidelity USB TO SPDIF converter, into a Bifrost DAC.
It sounds almost as agood as my analogue rig.
I play all formats (except DSD) and sample rates up to 24/192
I would suspect your problem may not be the file format
Regards