Once again, please dispel my doubts. It still seems to me that something is confused in the device with the modes of internal and external clocking. Today I was faced with new evidence. I have an old Sony diskman. Its inner clock is so imperfect that it reproduces the signal of 11025 Hz with a difference of 6 Hz (that is, like 11019 Hz). This device is full of jitter. But besides the linear analog output, the diskman also has an optical output. And what do I see when playing a signal through an optical cable on RME?
The difference of 6 Hz occurs only in the SRC mode (internal clock is on). When I switch to classic synchronization from the SPDIF source, the signal becomes ideal - all the extra peaks are disappear, and the main signal peak is exactly at 11025 Hz. Although it should be the other way around!