what is the best speaker for a flea power amp

Klipsch will work well.Try some La Scala's.WAF Factoe 0 but they sound good.
Tell her to evaluate them with her ears not her eyes.

The welbourne labs link is about the most complete for low powered tube stuff I've seen. The fostex and lowther drivers are efficient and have had a loyal following for years, although I don't know how high-fidelity they are. The only other company that comes to mind is Lambda acoustics. It looks like they market their systems as pro-audio and home, but they specs look nice. 102 and 108 db sensitivities depending on options w/ only a 16" square horn mouth. But they'll set you back $5,000 or so for a pair. The horn operates 300hz to 20,000hz with less than 1% distortion even at 110db across the band. The designer is a rocket scientist.

The new Von Schweikert db100's
Check em out at VonSchweikert.com

Typically a horn loaded speaker will be your best bet since
they are ususally very efficient.Go with a nice klipsch or
altec lansing speaker.You will be very pleased.
89vett