you'd be surprised at some of these first generation CDPs. after spending roughly 5 hours tinkering and 5 hours listening, my latest 1983 model sony CDP-11s acquisition sounds not much different from the high-priced ES classics of Sony. got it yesterday afternoon and finally sang by 3 a.m. this morning. this unit was bought at an amount equivalent to 7 liters of gasoline.
i have disassembled its boards due to some problems last night and noticed the premium components, very different from the usual less than 5-kg CDPs, including new production gear. i never had listening fatigue in the first three hours of operation this morning at room-loud volume level. the next two hours, was comparatively louder - party level - since it was almost noon. after more than an hour, i felt listening was not so pleasant anymore.
of course, this is my personal appraisal of this vintage CDP and may not apply to others. as far as i know, i have tuned my room to my listening preferences and the associated equipment were more of mid-level hifi models, not TOTL. gear used were Marantz Esotec 5 and Design Acoustics PS-10 speakers. music changed from Ryan Cayabyab and SMC Chorale, Mormon Tabernacle Choir, Asin, Julia Fordham, and Dixie Chicks (Natalie Maines sings well but listening to her voice for over an hour is too much.).