I know that at least some Church Fathers were fine with musical instruments. Gregory the Theologian, for example, said of David:
"Among the kings, David is celebrated, whose victories and trophies gained from the enemy are on record, but his most characteristic trait was his gentleness, and, before his kingly office, his power with the harp, able to soothe even the evil spirit." - Oration 43, 73
I think the main issue is whether they ought to be used in worship services or not, with the Orthodox falling on the "not" side.