Most devices have audibly transparent DACs, even if measurements aren't the best in the world the reality is that unless you are unlucky enough to buy an outlier or faulty product then the DAC will be fine. What is more likely to be worth upgrading is the headphone amplifier, assuming it has a headphone jack. Many of these devices have perfectly satisfactory headphone outputs too but hearing protection regs in some regions means volume may be a bit low, particularly if you have inefficient or hard to drive headphones. In that case the JDS Atom is cheap, powerful and with superb measured performance.