Tower of Power is an American R&B and funk based band and horn section, originating in Oakland, California, that has been performing since 1968. There have been a number of lead vocalists, the best-known being Lenny Williams, who fronted the band between early 1973 and late 1974, the period of their greatest commercial success. They have had eight songs on the Billboard Hot 100; their highest-charting songs include "You're Still a Young Man", "So Very Hard to Go", "What Is Hip?", and "Don't Change Horses (in the Middle of a Stream)".

Source: Wikipedia (https://en.wikipedia.org/wiki/Tower_of_Power)