Good news!
From what little I just read about this I see absolutely no harm. Here's why,,,
Based on my understandings from a book I read called, "This is your brain on music. The science of a human obsession" by Daniel Levitin.
A short overview, this guy was a neuro scientist, that studied the functions of the neurons in your brain. It was once thought that these neurons were what made up human thought and emotion. But,there's another science that branches off to try to understand the "Mind". It's odd how we seem to have a "Mind" as in personality, individuality, etc,, and also a brain, that controls all of this,, or is used by us.
Anyway,,,,,Here's the Music part, (sorry if It get's long, I absolutely love this stuff, as I'm a musician, and love music)
Basically, your brain is crontroled by neurons,,, these "fire" when certain parts of the brain are used for different things. For everysingle musical note, there is a single neuron or set's of neurons for that note.
Example,,,, When you hear an F#, you have a neuron in your brain that registers this particular note. On top of that, this particular deal, causes other neurons to fire and to signal the other neurons, which generates memories or emotions. On top of this, when you hear a song, it has many notes and tones from many different instruments. You end up with all this brain activity that stimulates several other things in your brain.
Your brain also keeps time with everysong within 1 beat per minute from the orginal time. In 4/4 time your brain is automatically keeping track, and count of the beats per measure.
You don't have a neuron that fires for the Colors,, such as,,, nothing happens in your brain when you see blue, there's no "Blue Neuron" as there is the F# neuron.
Anyway, this is very oversimplified, and I can't do any justice to the explaination. Check the book out if you have a chance.
As for my opinion, as long as none of this is suggestive of some sort of "spiritual" mumbo jumbo, and it's purely notes of the tonic scale to stimulate brain activity and generate a relaxed meditative state, I see absolutely nothing wrong with it.
The Lord wants us to meditate on Him and His word, the Lord loves music, and I believe it's a gift to us.
Why not use the benifits of Music as we would the benifits of an apple. Different nutrients for different things.