OK i like the idea of using one AA bat so i will go for the first gen NH600 or NH700 or NH800. Becouse of our stupid sony suplier we have only this versions in my country and the NH900, but the positive side is that i can get them all new. The only diference that i see between the NH600 and the NH700 is mic-in (that i dont use) and that there is no remote. Is there other things that difrent (sound quality or something like that) ?