Hi Mark
Yes this is a virtual battery that charges as you go when attached to the power. You can run the unit without the power supply if required but this will flatten the battery at some point. So as you said it will just keep charged when plugged in and need no maintenance. The idea is the unit runs off the battery so the mains electric supply noise(if any) is reduced if that makes sense. But the battery is always charged if plugged in. Well thats how I think it works This is an earlier model than the reference 2 but has everything you need including the MC/MM switching etc. Hope that helps. It is a few years old now and the models and specs change all the time on the newer versions. Still a very competent bit of kit.
Technics SL1210 MK2 fully rebuilt and repainted. Ortofon 2M Black Cart, Isonoe isolation feet , MN bearing and Funk Firm platter upgrade, Oyaide RCA Tone Arm and speaker cables, Jelco SA-750D Tonearm. Oyaide HS-TF Carbon headshell, MCRU Linear External PSU, High Fidelity Crystal glass turntable matt, Blue LED upgrade, Denon AVR-2808CI Amp, Bowers and Wilkins DM602S3 Speakers,
Black Rhodium Jazz power cables for amp and turntable, Firebottle mk2 Phono Stage.