Why not just kirtana? But why also japa? Because kirtana we do together and together we are taking inspiration from each other. When all together we are chanting with lots of feeling, even someone who’s heart is made of stone is sort of melting. Even someone who’s cold like a frog will feel something. So even if we have no feeling, when the chanting is very sweet ad very melodious in bhajana, it touches us and even brings out some feeling in the heart of everyone. In this way, at that time, we are approaching Krsna through reciprocation. But in japa we are going alone before Krsna. That is our time, our time alone with Krsna and in japa we go before Krsna as we are. There is nothing to hide. We are as we are!
In japa it is not the same as in bhajana. In bhajana we get swept up, we swoon, we feel the sweetness, we taste it, we say, ‘yes this is great!’ In japa it’s like a cold shower- at first we get faced with ourselves, with our lack of bhakti. We are facing that we actually have no devotion at all. In japa we get a mirror held up to ourselves and we fall short. Every little bit of bhakti that is lacking in us is just being mercilessly exposed and we have to face it, ‘I have no devotion at all...’ that is japa. Of course, japa is more than that; that is japa performed in sadhana. But as we continue to chant japa, japa will remain with us; japa is the one thing that stays.
(Kadamba Kanana Swami, 04 July 2010, Phoenix RY, SA)