Note on 28 June 2021 : Note from the designer: The kx2 Amplifier completely solves the difficulties some builders of the kx-Amplifier experienced. The new kx2 Amplifier offers improved distortion performance, nearly 20dB lower noise levels and the ability to switch between class A, class AAB or class AB. Further, the amplifier compensation can be jumper selected for TMC or standard Miller. The PCB uses the same compact format and heatsink mounting holes of the original design. The new kx2 PSU board includes a diode snubber which helps to lower switching noise. Full details of the design and documentation can be found in hifisonix website. We are authorized by the designer to manufacture and sell his boards. Each set consists of two amplifier PCBs. NO PSU PCB is included in this listing. We have another listing that includes the PSU PCB. Each amplifier PCB serves one audio channel. Boards dimension : Amplifier board ( just the rectangular dimension quoted) : 111mm x 67mm PCB thickness : 1.6mm Copper thickness : 75um( 4 times standard thickness) Surface finishing : Gold-plated with solder resist coated on both side for best reliability. We do air shipping worldwide at US$6.50. We welcome combine shipping.