Favourites, including (attributed) Twain:

It's been through three wives. To me a guitar is kind of like a woman. You don't know why you like 'em but you do.
Waylon Jennings

Music makes one feel so romantic - at least it always gets on one's nerves - which is the same thing nowadays.
Oscar Wilde

PIANO, n. A parlor utensil for subduing the impenitent visitor. It is operated by pressing the keys of the machine and the spirits of the audience.
Ambrose Bierce

Wagner's music is better than it sounds.
Mark Twain

Take a music bath once or twice a week for a few seasons, and you will find that it is to the soul what the water bath is to the body.
Oliver Wendell Holmes Jr.

Anybody who has listened to certain kinds of music, or read certain kinds of poetry, or heard certain kinds of performances on the concertina, will admit that even suicide has its brighter aspects.
Stephen Leacock