Experience with CSL 900 MBit Powerline adapters

Positive on these adapters is that they worked at first, were easy to encrypt and also in combination with other D-LAN adapters (for me Tecknet AV500) function.
Negative (and for me the main reason for return) is that one of the adapter emits a high-frequency whistle, what really bothers me a lot and causes headaches. From the reviews here starting seems unfortunately to be an isolated case. Furthermore, I was with the 900 Mbps adapters no increase in speed compared to my 500-Mbit models find even if only the two 900 Mbit model were in power. On my 500 Mbit models to reach real loud utility between 200 and 300 MBit.
Software (.. Drivers, utilities or similar) was not included - on the homepage of CSL, I could not find a suitable model for this utility. Judgment on the speed therefore only to hand the copy utilities (TeraCopy).