Triple Platinum Matched on Amplitrex AT1000 – TESTS NOS. Amplitrex AT1000 Test Results 90%+ GM = Within NOS Specs 90%+ EM = Within NOS Specs. RCA 2A3 Triode Power Tubes (Pair). All tubes are tested with the Audiophile in mind for SHORTS, GAS, MUTUAL CONDUCTANCE and NOISE (large tube lots are not tested for noise).