A high quality external master clock matters. The clocking of digital audio signals is crucial to achieve the highest transparency, a better clock simply gets you closer to the heart and soul of a performance. In your case, you would need to step up to Esoteric G-01X or G-02X master clock to make it worthwhile. Either a G-01X or G-02X connected to K-01XD and N-03T simultaneously will improve the performance of both devices. Don’t sweat the USB connection, you may end up preferring Coax over USB and vice versa.
I recommend a loaner G-01X or G-02X clock from your dealer with good BNC clock cables and Coax Cable and dive in. Implementation is a key here, this level of performance is not cheap but totally worthwhile if your components are designed to accept a HQ master clock.
You may check out my digital system, both streamer and DAC are driven by master clock. Once you experience a properly implemented high quality master clock, you wouldn’t have it any other way.