The primary argument that hard-lined Regulative Principle folks use is that no where in the scriptures do we see instruments used in corporate worship. They dismiss the Psalmists’ references to instruments (although numerous) as in a non-corporate context. But what about this from 2 Chronicles 29?
20 Then Hezekiah the king rose early and gathered the officials of the city and went up to the house of the Lord. 21 And they brought seven bulls, seven rams, seven lambs, and seven male goats for a sin offering for the kingdom and for the sanctuary and for Judah. And he commanded the priests, the sons of Aaron, to offer them on the altar of the Lord. 22 So they slaughtered the bulls, and the priests received the blood and threw it against the altar. And they slaughtered the rams, and their blood was thrown against the altar. And they slaughtered the lambs, and their blood was thrown against the altar. 23 Then the goats for the sin offering were brought to the king and the assembly, and they laid their hands on them, 24 and the priests slaughtered them and made a sin offering with their blood on the altar, to make atonement for all Israel. For the king commanded that the burnt offering and the sin offering should be made for all Israel.
25 And he stationed the Levites in the house of the Lord with cymbals, harps, and lyres, according to the commandment of David and of Gad the king’s seer and of Nathan the prophet, for the commandment was from the Lord through his prophets. 26 The Levites stood with the instruments of David, and the priests with the trumpets. 27 Then Hezekiah commanded that the burnt offering be offered on the altar. And when the burnt offering began, the song to the Lord began also, and the trumpets, accompanied by the instruments of David king of Israel. 28 The whole assembly worshiped, and the singers sang, and the trumpeters sounded. All this continued until the burnt offering was finished. 29 When the offering was finished, the king and all who were present with him bowed themselves and worshiped. 30 And Hezekiah the king and the officials commanded the Levites to sing praises to the Lord with the words of David and of Asaph the seer. And they sang praises with gladness, and they bowed down and worshiped. (Bold mine.)