 It reached its commercial peak in the mid- to late 1970s with acts like Billy Joel, America and the reformed Fleetwood Mac, whose "Rumours" (1977) was the best-selling album of the decade.In contrast to soft rock, hard rock was more often derived from blues-rock and was played louder and with more intensity.It often emphasised the electric guitar, both as a rhythm instrument using simple repetitive riffs and as a solo lead instrument, and was more likely to be used with distortion and other effects.