Yes, Fagen has great ears and knows what he wants. Nichols is an excellent engineer, but let’s not forget the role of the producer. Gary Katz produced many of their records including “Gaucho” as well as Fagen’s solo outing “The Nightfly”. You may find this interesting:
https://youtu.be/6as4nnjYRyY
https://youtu.be/6as4nnjYRyY