And also, keep in mind that Daddy MacManus was a professional singer who, it is said, was quite good for his time. I have never heard his father, but I often wonder how similar they are and if young Declan got a lot of tips just from hearing and watching his Dad.
You mentioned how Elvis will now in concert stand alone on the stage and sing without amplification or accompaniament. I saw him do this a few years ago and again, he killed me. It was as powerful as watching Pavarotti singing an aria. Incredible control!!!!
We'll have to see what happens to Elvis in coming years. He is about 52 now, a point in time where the vibrato starts getting wider and harder to control and the range starts to shrink. Statistically speaking, he may not have many years left to produce new vocal masterpieces. But, knowing him, his writing will change with it and he will still continue to be the only one capable of singing his songs.