The RCS 2.2 is an earlier system than the current RCS2.0. It had a build-in crossover for left/right channel and stereo subwoofers and could do correction for main-speakers and subwoofers separately.
The RCS 2.0 is newer, but does not have the crossover function. It will still do correction for main-speakers combined with subwoofers. However, the crossover has to be done after the RCS2.0 (for example in the subwoofer or with an external electronic crossover)
Furthermore, the RCS2.0 has better software (easier to use and faster to setup) - it is easy an inexpensive to upgrade due to the modular design and can be configured with different in- and outputs. The 2.2 was only available in one version: analog+digital in, only analog out. The 2.2 only supported 16bit/44.1khz. and had 20-bit internal resolution. The RCS 2.0 supports up to 24/96 - with optional 24/96 DA and AD boards - and can be upgraded to 192 khz. in the future. The software for 2.0 is also upgradeable.
