Sorry--too many messages today. O2 is still comfortably in production. The power jack difficulty was resolved in 2013. All components are available without constraint at this time. We did produce an O2 SMT derivative in 2013 for experimentation. The project was abandoned, so as to avoid licensing upsets. Additionally, there was no benefit to such a project. Performance was the same, but could not be improved. O2 is thermally limited by its chipset.
The Element uses a similar amplification topology (pre-amplification --> attenuation --> buffered output). Similarities end there, as the amp consists of a completely different chipset with optimal voltage planning to accommodate true line-level input and significantly higher output power. The Element uses microcontroller and relay based power management, and muting during startup and shutdown. See also
Circuitry and
Benchmark Performance in the
release article.