HA-1 is a portable amplifier made in Japan. MH Audio has been produced. There are not many production number. You can buy some at the store (Tokyo, Osaka).
iBasso P3+ Portable Headphone Amp Main Features: - ThreeChannel/ Four Channel compatible architecture - Totally 8 gold-plated DIP sockets for opamps and buffers rolling - 2-Setting Gain Jumper for impedance matching - High quality components, such as, gold plated PCB, ALPS volume pot, Nichicon cap, Vishay resistors, Switchcraft jacks. - Powered by either 6 AAA batteries or external power...
The CORDA HEADSIX is essentially the same amp as the XXS. However, this model is a low-profit project and for every amplifier sold $15,- will be donated to Head-Fi, the home-base of the internet-headphone-society. The amp is produced in a limited series of 600 pieces.