Music that doesn't give me headaches

Usually when I listen to music while reading or doing something requiring concentration, I get a bit of a headache. However, I have found 2 CDs that do not  give me a headache when I am doing something else.

One of them is the transcriptions of Bach organ pieces for piano I mentioned earlier.

The other is a 2-CD set called Glorious Pipes, which is basically a bunch of famous organ pieces. It's good to turn up the volume when listening to this one.

It's all good stuff, but I find that I particularly enjoy the last two pieces, written by Olivier Messiaen, who was a major composer of the 20C. He found birdsong fascinating and incorporated it into his works. I hadn't heard of him before.