I am researching options for building a highly efficient audio system for use with solar power. The goal is to obtain as much quality audio as possible from minimal energy input, such as 25 watts or less. The amp I am considering is based on the Tripath TA 2024 chipset. See http://www.michael.mardis.com/sonic/start.html for details. I am looking to find a good set of efficient speakers with >93db sensitivity to match this amp. Something with good midrange performance at around 7-8 watts per channel would be ideal.

Do you have any recommendations for a pi speaker?

Sadly, my solar array could not muster so much as a barely audible bleep from one of those vintage Sunn behemouths. So I am stuck figuring out how to make sounds that somewhat resemble the classic tube amp by generating high frequency pwm waveforms with my solar array and switching them into drivers with different response characteristics. The sound you can get from class d amps from only 15 watts still amazes me.

Not to mention the incredibly small size of these things - you could easily hide several inside a speaker cabinet:

... or Steven Mark(s) "secret" TPU Toroidal Generator.
, or else chinese?!
(http://www.zpenergy.com/modules.php?name=News&file=article&sid=2206)
(http://jeanyves.hervouet.free.fr/JapRod/)
But for now, solar is not bad at all, I agree. Save the planet.

• Toroidal Generator