There is no size limit to connected USB hard drives, however you may encounter problems if you have a very large collection on a high capacity drive. The memory included in the EVO that is required for indexing tracks from USB local Media is limited and may not be sufficient for such large collections.
Some larger capacity drives may also require you to use their own power supply, as the player's USB port may not supply enough power for the drive to function.
The primary function of the EVO is as a network music player. The USB ports are intended for convenient connection of USB thumb drives. As such, we cannot guarantee compatibility with all USB HDDs.