I think that, within limits, an increase in volume is perceived as an increase in the energy in the music, which is why it is preferred by most people. I do think that most music has a 'natural' level, at which the full degree of expression in the playing is realised (to the extent of the system's capabilities, obviously).
I also think that the design of amplifiers tends to mean that playing at a (comparatively) low volume will result in dynamic compression, hence why there is this 'natural' level. Also, of course, at higher volume, the SNR tends to be greater.
I'm not sure what Raga's taste in music is like, but if he's listening to a lot of compressed pop and rock, for example, the compression inherent in listening at lower levels might not be so apparent.