LEGACY PRODUCTS INCLUDING PROLOGUE ONE, TWO, FOUR, FIVE, SIX, SEVEN AND DIALOGUE ONE, TWO, FOUR, FIVE, SIX, SEVEN
Please refer to the list in your owner’s manual, with this addition: All PrimaLuna products from day one can use the newer KT120 tubes. All DiaLogue models can use KT150 tubes, the ProLogue cannot.
Models that came stock with EL34’s (the ProLogue One, Four, and Six and DiaLogue One, Four, and Six models) can have the bias manually adjusted "hotter" on the Adaptive AutoBias board to work better with these “larger” tubes, resulting in more dynamics and pop. Click here for instructions. The newer series products like ProLogue Classic, ProLogue Premium, and DiaLogue Premium do this for you by having an EL34/KT88-KT120 switch.
You cannot use KT150's in the original ProLogue series amplifiers. Only the original DiaLogue series amps can use them.