High efficiency speakers
The headphone amplifiers you listed would not make good amplifiers for speakers because the impedance of the output stage needs to be matched to that of the speakers for maximum efficiency.
There are a number of single ended triode (SET) tube amplifiers on the market that are designed to drive high efficiency loudspeakers. Think Cary Audio, Antique Sound Labs, and others.
The really high efficiency loudspeakers (>99 db/1watt/1meter) are always horn-loaded designs and are large and expensive.
Some companies offering medium-high efficiency (>95db)speakers to check out would include:
Moth Audio: http://www.mothaudio.com/
The Horn Shoppe: http://www.thehornshoppe.com/
If you are willing to buy used, the classic Klipsch loudspeakers such as the Klipschhorn, Cornwall, Belle Klipsch are all large horn loaded speakers that offer efficieny of between (100 and 104db). These show up used on eBay, but shipping costs can be prohibitive unless you can pick them up locally.
A slightly smaller yet still reasonably efficient (96db) Klipsch speaker would be the Heresy or Heresy II. These show up used on eBay frequently and sell there for $400-500 USD.
Good luck in your search for the perfect, low cost, high-efficiency loudspeaker. Please let us know what you ultimately decide to do.