As much as I understood from different reviews and tests, Chord Mojo is one of the best DACs in its price class. At least among USB DACs.
Some of the reviewers, said that it is even better than most of the DACs under 1000 EUR.
A serious update would be a jitter bug (e.g. from AudioQuest) and/or an audiophile power supply for the DAC (e.g. SBooster).
You could try to find something better on I2S or USB, but this depends on your complete system and the synergies between components.
Do not forget, that 80% of the differences are made by loudspeakers.
The only possibility is to try and listen: IMHO measurements do not tell necessarily very much about the musicality.
If you found something better, please tell us!