Fleetwood Mac Remixes

[MacMan]

It refers to the Phil Spector sound:

The Wall of Sound

Spector's trademark during that era was the so-called Wall of Sound, a production technique yielding a dense, layered effect that was very effective and dramatic, and carried especially well on AM radio and jukeboxes. To attain this signature sound, Spector gathered large groups of musicians (playing some instruments not generally used for ensemble playing, such as electric and acoustic guitars) playing orchestrated parts — often using many instruments playing in unison — for a fuller sound. Dozens of musicians and instruments would be jammed into Spector's tiny Gold Star studio, with the sound reverberating off the walls adding to the effect.