1984 - 1989 with PLS-124 external power supply.
This small preamp does'nt have any power supply. The first model, the ML12, uses the amplifier ML11 power supply throught a pair of (custom) cables. The PLS-124 is a special external power supply, if you don't have an ML11. Actually it's maybe easier to buy an ML11 than to find a PLS-124 I guess !