Thanks for taking the time to design these and submit! #39 is very clever, as you either see a "T" or an "M" depending on how you look at it. However, if there were two letters I'd want prominent it would be the T and L, because we may not even use the word Music. I chose it over #40 because I didn't like the blue and green combo.
On #38 I really liked the font and the clever beaker hidden in the U, but it actually took me a second to figure out what that was. Not that our target audience is slow, but I'd prefer something a little more obvious. I'm not sure if that can be accomplished within the same idea. The other thing I didn't really like in it was the multiple colors. I'm seeing greens, yellows, darks, blues, and oranges in the same logo, and if you look at www.tunelab.com, all you see (not counting album covers) is green, black, white, and grey.