Your device's audio output may not be running at 48 kHz. This can cause brief pitch changes.
If you hear that, try setting your system's audio output sample rate to 48 kHz.
Not connected
Buffer: latency vs. smoothness
A larger buffer rides out network hiccups more smoothly, at the cost of a longer delay.
Hearing dropouts? Try the next preset up. Longer buffers add delay but ride out network hiccups and late-arriving audio.