I agree with the previous posters 100%.
In addition, take in to account that the reason one has their tonsils removed in the first place (as was for certain in my case) is that they are probably experiencing frequent sore throats or vocal discomfort and swelling, which all affects the sounds one can produce.
After the operation these uncomfortable feelings will be lessened or gone completely
Just the fact that I felt much better physically (without constant throat pain) made me happier and well rested, which allowed me to sing much better!
"To love another person is to see the face of God!"