Digital Drive: Unfortunately it isn't that simple. by PAR

One reason why I have asked the OP what sort of device from Amazon he has.

If he literally has a Kindle then he will not be able to do this. It is a dedicated e-Reader running what appears to be a proprietary OS. For him to do what he wants he will first need to install a media player. I do not think that is feasible on a Kindle not just from a technical point of view but it may also infringe Amazon's T&Cs leaving it open for them to simply disable the device. Kindles also only support various text publishing formats and Audible books.

If he has instead an Amazon Fire tablet then this may be feasible. He may be able to install an Android music player. The best that I know is USB Audio Player Pro. However they do not list any Amazon device in their list of compatible devices. The list is not comprehensive but that still leaves the question. Not all Android devices are configured to allow digital sound output via the USB port so this needs to be established. I had to reconfigure my Samsung Galaxy 7 via the developer screen to allow this.

The memory for Fire tablets is not great and if he wants to listen to more than a handful of hi-res albums downloaded from HD Tracks (to a music folder that he may need to create on the device) he may need to expand the memory using an SD card.

Finally with most (all?)Android devices such as Fire, connection from the micro USB port to a DAC may require a Micro USB to female USB A On the Go (OTG) cable. This requirement also needs to be established but if so a normal micro USB to female USB A will not work.