This is a kit of bare PCBs for an audiophile grade headphone amplifier, or preamplifier. The product features a main board and three interchangeable buffer modules. The main board contains a low noise gain stage to provide high impedance and voltage gain for the input signal. The buffer modules have different circuit topologies so that while all of them offer high speed and high driving current performance, each has its own sonic signature too. The three modules are respectively : 1. High speed high current diamond buffer using discrete transistors ( An application example being HDAM-SA module); 2. LME49600 ultra low distortion, ultra high speed buffer ; 3. BUF-03 high speed high current buffer in PARALLEL. Operating voltage : DC +/- 15V. We recommend low impedance shunt regulator or Kubota series regulator for power supply purpose. In our shop we have low impedance shunt regulator, Borbely low noise shunt regulator board and Kubota regulator boards/kits which can serve this amplifier very well. PCB dimension : Main board : 128mm x 125mm. Module board : 30mm x 28mm each. We provide schematic and part list to buyers. We do air shipping worldwide at US$5.50.