I saw this post a long time ago, but I actually never answered, which I should have had. These kinds of tests are very valuable and it should be acknowledged! Thanks for posting!
Very recently I started to search for mini speakers and now I found some specifications that I never had seen in the past. I don’t know if I didn’t search well enough before, or if these are just reaching the market. For example, there are round speakers of about 30mm with 6 or 8 Ohm and 20W. I don’t know the quality of these, but it would certainly be interesting to try. My question is; what is the voltage output from the teensy directed to the speaker? I suppose that a speaker with a high Wattage rating is still restricted by the voltage that doesn’t allow the speaker to use its full potential. I found a forum with a discussion about this issue using Ohm’s law, and if I understood it correctly, I can keep the voltage and resistance constant and calculate the power.
Ex Ohm W V Amp
1 4 6,25 5,0 1,25
2 6 4,17 5,0 0,83
3 8 3,13 5,0 0,63
4 4 3,42 3,7 0,93
5 6 2,28 3,7 0,62
6 8 1,71 3,7 0,46
7 4 13,69 7,4 1,85
8 6 9,13 7,4 1,23
9 8 6,85 7,4 0,93
Now, to be fair, the actual impendence will vary, but the calculation is just to get an idea. Another question is if a speaker rated to 20W will still sounds better than 3W speaker. In the video, the last speaker is clearly the "winner", but maybe the key advantage is the large box that holds the speaker. I added the last three lines to see how a 2*3,7V option would work. Please correct my if I have misunderstood something.