Dennis’s first recording with Na Leo O Nu’uanu was an album entitled ‘Ia ‘Oe E Ka La Volume 1 on the Nakahili Productions label with Palani Vaughan. It was the first of a series of albums based on the life of King David Kalakaua. The second recording of the group in 1974 would become historic in the Hawaiian music genre, the album was recorded live at a music festival in Waimea, Hawaii called The Waimea Music Festival. It was the Hawaiian Woodstock of the 1970s and featured many of Hawaii’s popular entertainers of that time including Gabby Pahinui, Fred Punahoa, The Sunday Manoa, and Genoa Keawe.
It was his tenure with (Eddie Kamae) the (Sons of Hawaii) (1974 – 1995) that would lead him to become one of Hawaii’s most prolific songwriter in the Hawaiian language, composing 500 songs. Many of his songs became Hawaiian classics, including Pua Hone, Wahine ‘Ilikea, E Hihiwai, Koke’e, Golden Stallion, Selamoku, Hualalai, Kou Aloha Mau A Mau, Na Makani ‘Eha, Na Ali’i Pu’olani. In 1974, Dennis recorded with the Sons of Hawai’i for the National Geographic Society’s Music of the World series. It would be the beginning of seven albums under the Hawaii Sons label and the recording of many of his music compositions. In 1978 he became a member of the American Society of Composer, Authors, and Publishers (ASCAP) and created Naukilo Publishing Company, a music publishing firm.