Rolls PA555 Tube PreamplifierThe Rolls Bellari PA555 is a tube preamplifier for line level sources including DAC, phono stage pre, CD players, and mobile devices. It sports three sets of stereo RCA inputs and a 3. 5mm input for computers, smartphones, and other appropriate sources. With the onboard switch, you can choose among the inputs and route them to the stereo RCA outputs. The PA555 uses a 12AX7 tube running at 150 volts. The input signal is connected directly to the grid