DCstep, you are probably right re Barber -- a little dark and different by comparison with Cassidy, but great range/voice as you know. The song showing of her skill would be "too rich for my blood". A great test for your hardware.
Some of Cole's work is a little lighter. I am taken with her song "Trust In Me" from the Jungle Book (if you know the movie context), and "I can see clearly now", which is a song that has nauseated me over the years, but is suddenly injected by Cole's magic.