Thanks to all! I just found the answer. In short: Atrac3+ devices has no ATRAC1 write capabilities. If You want to write an SP, You must use SonicStage. Tracks are converted by computer and transfered to portable like a data. It means, that when portable is switched to PC, it doesn`t understand what does it writes. It writes all kind of files, which are converted and ordered by SonicStage. But, SonicStage converts all media files only for ATRAC3 compartible units. Have You seen the note "Transfers the file in SP mode for compartibility with "non-MDLP" devices"? SonicStage converts all files to LP ONLY! But for compartibility with "non-MDLP" it puts an false-data intervals in file and makes it larger. Also the ATRAC3+ unit, when plaing TRUE-SP file thinks, that it is emulation, and skips noted above intervals. For experiment i wrote an SP-track and an LP-track by SonicStage. I was sad then I have`t find in listening any kind of differences in they. So, conclusion: If You want to listen a full-range good SP, You must write it on the on ATRAC 4.5 unit, and listen it on the same one. If You are not agree, then just try it.