Can I use a NAS or a SAN for the mass storage of the audiofiles?

Both types of mass storage can be used. From the perspective of the recording server, a SAN volume is shown as a local harddrive. There is nothing special you need to do. A NAS is like a file server which has some shares on which data can be stored by the LogDepot. When a NAS is used, it needs to be configured to have two  shares for LogDepot: one share to store the LoQ audio files and one share for the HiQ audio files.