To answer the OP question, YES, this is sales guy BS. The Deluxe & Deville are two different amps. One is designed to output 40 watts, the other 60. The circuits are similar but the supply voltages are different as I noted already. No way will any load change affect the output wattage to any significant degree. Whatever differences are heard are the result of different speakers/quantities/cabinets. Give it a rest.