We would like to declare a moratorium on the use of the term "chamber pop." It doesn't mean anything. Belle and Sebastian/Elliot Smith/The Decemberists don't write chamber music, and their music isn't written in a chamber (despite evocative cover art featuring Kafka).
The closest teleological cousin we can think of to "chamber pop" is Chamber Music, Joyce's (terrible) book of poetry, which title, though, puns on and refers to the tinkling sound of a woman making water in a chamber pot. So when critics (it's always critics, the lice between the sheets of great art) use the phrase "chamber pop," what they're doing is pissing all over your record. So critics: stop using it.
And Amazon? There is no genetic trait linking Evanescance; Sigur Ros; Rufus Wainwright; Goldfrapp; and Brian Wilson. Except overwhelming whiteness. So is that what Amazon thinks chamber pop means, namely whiteness?