Try this script snippet for the directory part:
$firstalphachar($if2(%albumartistsort%,%artistsort%))/
The following discussion about the sortname vs $swapprefix() might also be interesting:
Try this script snippet for the directory part:
$firstalphachar($if2(%albumartistsort%,%artistsort%))/
The following discussion about the sortname vs $swapprefix() might also be interesting: