There are multiple artists named Em:
1) eM is solo space ambient project of Michael Bentley, producing contemplative abstractions bathed in an inviting, dream-like warmth.
2) Em is a Polish rock band formed in autumn 1993. Founder is Mariusz Dalecki. The first year of eM is the year of tuning guitars. Later, there was a higher shelf: tuning the instruments to each other. Today Mariusz says he was the first name, and then skills. Attention was this rather unusual name of the band. Read more on Last.fm