@lou_setriodes per Stereophile, the differences between the original RM-9 and the RM-9 MK II:
Let’s take a closer look at the Mk.II. The output power has been nudged from 100 to 125Wpc—[an increase of 1dBW—Ed.]—the new wood frame is more visually pleasing, and the On/Off switch is now rocker-style. The five-way binding posts are new—they’re made of solid copper, have ¼" studs, and are altogether more pleasing to my sensibilities. The output-tube fuses are now top-mounted together with "Fuse-Out" indicators—a major convenience—and the input/driver tubes are 6922s, tested by RAM Labs.
But the most significant upgrades—those in the power supply—are invisible. Capacitor energy storage, for instance, has been increased by 50%. Most significant, according to Roger, are the dual chokes that have been added to the power supply beyond the existing filter network—a filter dedicated to each channel. These chokes not only improve the filtering action, but also serve to improve right/left channel separation. Best of all, the RM-9’s retail price is almost the same as it was in 1989: $2950 in oak with an EL34C output-tube complement. Additional finishes and output-tube complements (eg, KT88s) are available as options.