Here's a vid of the MP10W on a 37 G aquarium. The person that made the vid cycled through the different modes to show the sound for each. After looking at this it seems like the Reef crest mode which i use on the 40 is the least oppressive lol... But at least this gives you an idea of what it sounds like
http://www.youtube.com/watch?v=9cI_BG2sUZw
Here's a pretty nice wave made on a 36" 30 G tank..
http://www.youtube.com/watch?v=Q3RYioaSFvI