Listen to Shouldn't I Know online. Shouldn't I Know is an English language song and is sung by The Cardinals. Shouldn't I Know, from the album Love potion Number Nine - 200 R&B Hits (The Greatest Rhythm & Blues Classics of the 50s & 60s), was released in the year 2016. The duration of the song is 3:10. Download English songs online from JioSaavn.