Musical instruments are always an interesting topic. Most pro-instrument debators return to David and his instruments at some point for support. Yet Amos actually disproves using David as an example. They got deported after using David as their example for inventing instruments. God had commanded David to make instruments and given him the psalms via the Holy Spirit. He was inspired and one of the few men who were. Claiming to exercise David's position as prophet was a serious matter it seems. The Psalms were written as God wanted them and writing our own as we thought the Christ would be, would be a sin.
If God did not command you to invent instruments it would be wrong to assume the role through past examples. The command, example inference hermeneutic wouldn't work here.
Amos 6:1-6
5 That chant to the sound of the viol, and invent to themselves instruments of musick, like David;
It is not stated God's reasoning exactly but it is clear that copying David in some cases brought God's ire. All the issues in the chapter aren't sins in and of themselves. Lying on a couch or using violins or having wine in a punch bowl aren't sins of themselves. Christ reclined and dipped sop in a bowl.
Yet, there is a context in which God sees all of these as sinful. Likewise, instruments were commanded and David invented some, music wasn't sin of itself; but in this Amos context it was sin. Copying David wasn't a precedent for others to follow.
God did not command the public to invent instruments or to use temple music as leisure. David's music wasn't leisure, the Psalms were meant for worship in public places, in the temple Psalms taught about the coming Christ. Music in our day is mostly leisure. It is sinful to mix leisure concepts into worship. They also anointed themselves with oil which God reprimanded. I'm not sure what that was about.
7 Therefore now shall they go captive with the first that go captive, and the banquet of them that stretched themselves shall be removed.
Just understand that inventing such music was against God's will. Life had become leisure, including the instruments employed. Sacred works were copied, people lost the distinction between holy and unholy. God removed them. Todays world might accuse God of not appreciating the arts and music and the finer things in life, but God had his reasons. Before making blanket statements about copying David as a precedent we should be careful.