I have been fighting with my D90SE for a few weeks. I have only one source that causes audio dropouts every 5-10 seconds. This is a streaming source and therefore has some clock jitter because of its syncronization mechanism with multiple home zones across a network. I have three other top-of-the line DACs and an Audio Precision APX555 and they all can track this source SPDIF Coax but not the D90Se.
I finally took it apart and extensively measured the signals on the input and the SPDIF receiver and found that is was not losing PLL lock as I had imagined when the dropouts occurred. This led me to believe that it was something downstream of the receiver (Incidentally the receiver chip is an On Semiconductor LC89091JA).
I wondered if there was a firmware update that might help. I searched and found version v1.87. I was several versions behind, but had never hooked up the USB, testing MQA decoding of the digital inputs mostly. So I didn't know what firmware version it had.
Well my digital dropout problem disappeared after I re-flashed to v1.87. At least they are greatly reduced. I was also able to reduce the jitter in the streaming device a bit, and now no dropouts. I also tested with a Benchmark DAC1, Benchmark, DAC3, Topping DX7s, and two different generations of Audio Precision analyzers.
Before the update the D90SE passed the Standard Jitter Tolerance Test that the AP can run. But it was still dropping out on the streaming digital output.
I am most anxious to ask if anyone else has seen an improvement in the SPDIF and OPT inputs like I have with v1.87.
Thanks,