Why should one use musical instruments to thank Hashem?
Radak: They arouse and help the Nefesh of Chachmah.
Malbim: They correspond to Hashem's natural conduct of the world, from the six days of creation without change. The worlds are arranged according to laws of music; morning stars sing together with all Bnei Elokim 1 .
What is "b'Nevel Asor"?
Rashi (from Erchin 13b): It is a lyre with 10 strings.
Radak: It is b'Nevel v'Asor; the prefix Vov is omitted. The same applies to "Shemesh Yare'ach" (Chabakuk 3:11) and similar verses. Asor is an instrument with Eser (10) strings 1 . The same applies to "Alei Asor va'Alei Navel" (below, 92:4).
Malbim: One should sing His Gevuros with Nevel Asor, correspond to the 10 spheres [on which the celestial bodies revolve].
