What does this update do?
Your L-81 accepts now memory devices formatted in FAT32 and SDHC cards. (Max. 16GB)
1) format a USB stick not bigger than 2GB in FAT
2) unzip the file on your PC
3) copy the unzipped files directly to you USB device
4) connect the USB stick to your L-81 and switch on
5) select USB with button AUDIO SELECT and wait minimum 60 seconds
6) upgrade is finished, switch L-81 off and disconnect USB stick.
Firmware download link: