@reubent: One problem with the Pet Sounds album is that the multi-track is not a very good recording to begin with; a good pressing can’t cure that, only not make it worse.
Brian had only 4-track machines to work with at that time, and did a lot of "bouncing" (taking a fully-recorded multi-track tape and mixing all four channels down to one, copying that mix onto one track of another 4-track machine and recording on the other three channels, repeating that process until he all the instruments and voices he wanted). All that tape copying results in the instruments and voices being several generations removed from their original recording. As a consequence, the finished tape sounds rather veiled, soft, and lifeless. It’s very hard to hear the piano playing the glorious chord progression of "God Only Knows", one of my favorite Pop compositions of all-time (McCartney’s too).
In December there is a new album from Brian being released---just him sitting at a grand piano, playing solo piano versions of a lot of his best songs, including "God Only Knows". Oughta be great!