I found some parts, marked with the AD sign and some letters:
and another case
The case looks like SOIC-8, and I think, they must be amplifiers.
Unfortunally, I did not find any reference list, where I could find out the part number to get a datasheet.
Google did not find anything, and in the Turuta SMD Code book I did not find anything.
What are these chips? And where is a small part mark reference for Analog parts?