IMHO, Andrea Bocelli and Sarah Brightman are in the same league. If they float your boat then by all means collect their CD's. I personally don't own any. I have been listening to the classical voice for over 25 years so by now have a pretty good knowledge and appreciation of a classical singer's art. A beautiful voice is definitely a good start, but it's the technique and art of delivering the line and the meaning of the text/lyrics that differentiate a singer's singer from a mere songster/songstress.
Callas does not have a beautiful voice but one only needs a few seconds of listening to her arias to recognize a legend.
Callas does not have a beautiful voice but one only needs a few seconds of listening to her arias to recognize a legend.