With the M Voice Expansion, the Waldorf M synthesizer can be expanded from eight voices to a total of 16 voices. The doubling of the voices is especially beneficial for Multimode, so depending on the sound (mono/legato/poly) and the voices used, there are still reserves without a voice theft happening. No technical expertise is required for the installation. Apart from a suitable screwdriver and a soft base, nothing else is needed. However, it is advisable to follow the installation instructions linked here.