Or musical instruments at all. But since Catholics (can only) imagine that the apparent but non-existent bread and wine they consumed is the true body and blood of the incarnated Christ (whose manifest physicality Scripture emphasizes in contrary to a christ whose appearance did not conform to what he materially was: Lk. 24:39; John 20:27; 1 John 1:1-3; 4:2-3; 5:6), then it is a grave matter for them when a Protestant to receive this. Even though only about half of the Catholics believe in transubstantiation themselves.
But doctrine is important, and the Catholic contrivance of the Lord's supper is just which is just one of the distinctive Catholic teachings that are not manifest in the only wholly inspired substantive authoritative record of what the NT church believed (which is Scripture, in particular Acts through Revelation, which best shows how the NT church understood the gospels).
NOW you have done it!!
Offended those who have only a pitchpipe to get them started singing.
They'll correctly point out that the NT church had no pianos or organs, and that's why they don't use them.
Of course, they drive their cars to church and read their bibles from electrical lighting fixtures, so ya gotta be selective.