I also have Sony HAP-Z1ES. I copy music files directly from Windows file manager without using the Sony Music Transfer program. Transfer using wireless is always slow, but transfer using wired connection is faster, up to 25 MB/s.
Unable to load files to Sony HAP-Z1ES thru network
I’m having difficulties transferring files—pretty much anything about 96kHz/24bit—into my Sony HAP-Z1ES through a wireless network. Typically, a few files will transfer, but then I’ll get an error message (in the Sony transfer app) saying a file can not be found. The transfer then stops. Any advice is greatly appreciated.