The lack of any "...pops and clicks..." indicates that your host (computer, tablet, smartphone, etc) is running well. These sorts of issues are always host side problems and what is actually happening is either a buffer under or over run condition. With proper setup and configuration, nearly any compliant host can be made to behave properly with an asynchronous device (which is certainly on the more challenging side). Keep in mind that an isochronous task (such as streaming audio) is much more demanding than a bulk one (like sending data to a printer, reading or writing a HDD, reading a mouse or keyboard input) as there is only one chance to get the data sent to the device correctly and on time. If the host can't keep up, then under or over runs (the former being more common) will occur and if it happens often enough, it will be audible.
In all HRT Streamer models, we have a routine in firmware that monitors the inbound USB data packets. If five or more in a row are corrupt (wrong number of bytes for the current sample rate and bit depth) the Streamer will temporarily mute the output and flash the mute LED to warn the user that their host isn't keeping up and should be 'tuned up' to better handle the task. If you notice that the mute LED is occasional flashing (even if you don't notice the event audibly) you should be looking to improve the host's performance.
The 'fixes' for different host's are different so I would always encourage anyone to contact our support department (email@example.com) as we have considerable resources at our disposal along with the experience (100k+ units) to assist.
High Resolution Technologies, LLC