An M-Audio stage piano is created by M Audio which is part of the US based Avid Technology group who specialise in audio products and equipment. The company was founded in 1988 and aims many of its products at the Djing market. It only offers one stage piano and 3 digital portable pianos.
ProKeys 88 M-Audio Stage Piano

This premium digital m-audio stage piano offers a large sound bank memory compared to its closest rivals. The 88 key hammer action keyboard is a favourite with pianists and delivers a vert realistic feel when playing. The on board EQ gives flexibility in the tone and has 3 build in reverb options to play with. It has a great master controller keyboard with a USB connection to your home Mac or PC. Ultimately you get a lot for your money and this is an affordable options when looking for a mid range digital stage piano.
For an alternative to M-Audio stage piano try a Yamaha stage piano