and AT ALL COSTS avoid things which "play [...] all 'classical tunes' - Mozart, Beethoven, Haydn etc, albeit rather electronic sounding!"

this is HUGELY!!! important. Whenever you can hear 'electronic sounding' you are hearing electronic and not musical sounds, even when they are emulating the classics. This is not trivial. I have nothing against electronic music, or electronics in music, but I came to some important understandings about musical sound(s) from a friend's textbook entitled, I think, The Physics of Musical Sound. As a nurturing person, you will appreciate that little ones' musical experiences ought to exclude 'rather electronic sounding' toys which will be cycled thousands of times.

good thread. and many happy years of finding age-appropriate REAL musical instruments.
keep on pickin'
dennis