Note:
Groups are identical in difficulty, according to my findings. If anyone can tease out the groups better than I could, please let me know! I found that many old instrument difficulties had changed or were different than I expected.
Easiest to Hardest:
lyre
sra'ajahh
pi tambura
kithara
angle harp
lap harp
faenellica
box fiddle
mandolin
sarangi
fiddle
lute
pi sitar
rebec
cistre
violin
cittern
gittern
large harp
psaltery
banjo
zither
Missing:
guti'adar