This is the first Plinius amplifier, along with the Plinius II pre-amplifier; there was no Plinius I sold commercially. Still a very good sounding amplifier combination, the pre-amp is short on facilities, tone & balance, but that really is a good thing, The simplicity of design makes this still a fine sounding amplifier. Plenty of power in reserve and well built these are still being used today I've put them up against modern amps that cost several thousand and these beat most...after a little TLC; capacitor replacement particularly.