Complex sentence: He can be heard on the group's live (and best selling) album, "Procol Harum Live with the Edmonton Symphony Orchestra", but left the group during the recording sessions for their 1973 album "Grand Hotel".
Split into simpler sentences: He can be heard on the group's live (and best selling) album, "Procol Harum Live with the Edmonton Symphony Orchestra". He quit Procol Harum during the recording sessions for their 1973 album "Grand Hotel".