The Counterpoint SA4 was designed by Roger Modjeski of Music Reference. It was an OTL amp, and he sold the design to Counterpoint, who manufactured and marketed it. Modjeski has some OTL's in his current Music Reference line. To find them do a Google search for Music Reference, and Music Reference / RAM Tubeworks will be the first site shown. Click on "Complete Price List" for a little info on all his amps, including the OTL's.
Not trendy, high-profile, or flashy (Roger's not a flashy kinda guy) but REAL good amps. His RM-200 Mk.2 is currently in the Stereophile Class A / Tube category, along with some way more expensive amps from trendier, higher-profile, flashier companies. Undeservedly under-owned. High owner satisfaction, very rarely for sale used.