Power over USB for digital circuits is just like all other digital loads. IT requires a very fast responding regulator. Batteries don't work very well for this, even LI. SMPS power supplies, at least the latest generation can respond very fast, but they also introduce noise due to the switching.
The optimum solution is a very fast linear regulator in a linear supply, like the Power Block. This supply is based on Hynes regulation technology, so it has the best regulator available. Extremely low noise and very fast regulation. No adapter cable needed.
Power supplies are the MOST IMPORTANT part of any audio system, whether for digital or analog sections. The Power Block is the best of these solutions. The others are just toys:
30-day money-back if you are not satisfied with the improvement, less shipping.