The EMI CD transfer has opened up the mono sound, putting air round the voices and instruments, giving presence. Where the earlier transfer of this set sounded disappointingly flat, this one is brighter, clearer, fuller, with textures clarified.
The voices better defined and separated.
A full stereo recording would have been better still, but it was this recording which Walter Legge would often cite in conversation, when he mounted his curious hobby-horse, questioning the value of stereo over mono. The scene he picked on was where children hear the cuckoo in the forest: there the distancing of the cuckoocall does indeed simulate stereo atmosphere, but that's far clearer this time than last.
The performance remains a classic, with Karajan plainly in love with the music, and the two principals singing immaculately. This isn't for those who resist the child-voice inflexion of Schwarzkopf and Grümmer, but everyone else will register the mastery in singing and acting.
The thinness of Anny Felbermayer's voice as the Sandman is an unwelcome contrast, but this is otherwise a satisfyingly Germanic team.