The 'popping' you heard was probably a case of overdriving the input of the MD recorder. If the MZ-NH700 allows you to manually set the recording level, you may need to turn it down. Also, don't use the automatic gain settings on the recorder. I agree with bjsilva's comments about placement. Bad placement can make a good mic sound bad. For classical singing, don't use a close mic placement like pop singers use. The voice needs room to expand before reaching the microphone, and you'll typically want some of the room acoustics as well. I've recorded dozens of band and choir concerts using the AT822, and it is an excellent microphone, but save your money and buy the adapter for the AT801. The AT801 should work very well for what you need. The one advantage of the 822 over the 801 is that the 822 is a stereo mic. Get some experience recording with the 801. If you decide later that you want to record in stereo, then buy the 822 or the Rode NT4. I'm also a classical singer, and just bought an MZ-M100 recorder. So far I've just been using it with the ECM-DS70P microphone that came with it. Eventually I'll get either the AT822 or the Rode NT4.
The 'popping' you heard was probably a case of overdriving the input of the MD recorder. If the MZ-NH700 allows you to manually set the recording level, you may need to turn it down. Also, don't use the automatic gain settings on the recorder. I agree with bjsilva's comments about placement. Bad placement can make a good mic sound bad. For classical singing, don't use a close mic placement like pop singers use. The voice needs room to expand before reaching the microphone, and you'll typically want some of the room acoustics as well. I've recorded dozens of band and choir concerts using the AT822, and it is an excellent microphone, but save your money and buy the adapter for the AT801. The AT801 should work very well for what you need. The one advantage of the 822 over the 801 is that the 822 is a stereo mic. Get some experience recording with the 801. If you decide later that you want to record in stereo, then buy the 822 or the Rode NT4. I'm also a classical singer, and just bought an MZ-M100 recorder. So far I've just been using it with the ECM-DS70P microphone that came with it. Eventually I'll get either the AT822 or the Rode NT4.