Which kinds of music should we listen to (if we are using music to reach our soul)?
Answer:The older the music is, the closer to holiness it is. In more recent times, the niggunim of Rav Moshe Shmuel Shapiro zt”l are considered to be the best songs to listen to (see samples online). Rav Wolbe zt”l said that these songs are extremely holy. There is no music on it, however, just words. You can hear them on Kol HaLashon. You can also buy the songs of Rav Baruch Ber Levovitz zt”l (online profile) in the sefarim stores which are from many years ago. These are very holy niggunim.