The K5PRO is a compact, desktop DAC/headphone amp combo by FiiO. It features the leading AK4493 DAC chip with a wide variety of inputs and outputs to create a great value proposition.
The Marantz HD-DAC1 is a stylish compact DAC and headphone amp that comes with USB and analog 3.5mm in. Though it does not have the best specs when it comes to audio decoding capabilities, it's a great sounding device.
32 bit / 768 kHz
24 bit / 192 kHz
Cirrus Logic CS4398
Audio Science Review
In that regard, and in the context of a budget product that is designed reasonably well, I am going to recommend the Fiio K5 Pro.