I'm planning to record my demo cd at school's practice room with baby grand Steinway. The repertoire is just classical piano, such as mozart, beethoven, schumann, brahms, and rachmaninoff. I'll record it with a field recorder H4n. Now i still need to get a good mic (or a pair?) From my research, it seems that some good choices include: Oktava MK-012, Shure SM57, and NT55... they are a little expensive for me though. Do you have any other recommendations? What's the best among these three? Do i really need to get a pair, instead of one? Thank you!