Crow Sister, was it the Ligeti you meant was difficult?

The baritone on the original LP was William Pearson, who also recorded Peter Maxwell Davies's "Eight Songs for a Mad King". He had studied with Roy Hart, who you can find on Wikipedia and at http://www.roy-hart.com/ . Pearson's voice had about the same range as a piano, or to be more precise, the range from the death agony of a brontosaur to a bat being castrated.

But the Wikipedia article doesn't come anywhere near telling the whole story, and neither does the official website. I once found a copy of the Roy Hart in-house fanzine. It seemed the only way you could really learn the Roy Hart approach was by moving into Roy's commune and having sex with Roy and everybody else in the house regardless of gender. I seem to have lost the fanzine at some point in the last 20 years and I kinda doubt if even the British Library has one. The only comparable organization I can think of was Otto Muehl's AA Model.