 Kọ itẹsiwaju fun paragirafi yii - Bibẹrẹ ni ọdun 1982, Shaffer ṣiṣẹ bi oludari orin fun awọn ifihan ijiroro alẹ ti David Letterman: bi adari The Worlds Most Dangerous Band fun Late Night with David Letterman 19821993 lori NBC, fun eyiti o tun kọ orin akori, ati bi adari ti CBS Orchestra fun Late Show pẹlu David Letterman 19932015 lori CBS. Letterman nigbagbogbo sọ pe iyipada ti iṣafihan si CBS jẹ nitori pe NBC fi Paul silẹ fun ji awọn pen tabi idi miiran ti ko ṣe pataki. Shaffer ṣe alejo-alejo ifihan naa ni igba mẹrin nigbati Letterman ko si: Kínní 9 ati 11, 2000, nigba imularada Letterman lati iṣẹ abẹ fifọ ọkàn rẹ; Oṣu Kẹta Ọjọ 24, Ọdun 2003, nigbati Letterman n jiya lati shingles; ati Oṣu Kini Ọjọ 19, Ọdun 2005, nigbati Letterman lọ lati gba ẹbun fun iṣẹgun ẹgbẹ ere-ije rẹ ni 2004 Indianapolis 500 : ó ṣe tán. 