I think some miss the point. Phil Spector took the genre R&R and (in his own words) “augmented” the more traditional size of ensemble used in R&R and through the use of larger ensembles and the exploitation of studio techniques created a sound often referred to as a “wall of sound”; same style of music, much larger presentation. Chamber music is typically Classical music for a small ensemble while, by comparison, Orchestral music is the same genre composed or orchestrated for much larger ensembles. Clearly an oversimplification and no qualitative judgment suggested, but same idea as Spector’s approach.