I think Charger's speakers are Martin Logan "Motion 15", as stated in his signature.
They are bookshelf with a sensitivity of 92 db, recommended amp are everything above 20w with a maximum of 200w.
I think a Gainclone could be a good match for them, as Michael wrote!
It's easy to build, cheap, good sounding, and with enought power to satisfy long-excursion woofers.
PS: It's also reported to work best with a tube preamp!
Ciao!