I remember a review of Diamond Dogs in "Audio" magazine around 1974.
These are a few choice quotes I remember concerning the the sound quality.
"The instruments wash around like last year's blankets in a wardrobe full of cotton wool"
"effects are layered in, one on top of the other; so much so that it's nigh on impossible to hear what the hell is supposed to be going on. It's as if they had 32 tracks so that's what they were going to use; every last one of them and damn the consequences"
"Bowie and Ken Scott did most of the mixes; fine, if that's how they wanted it, it's a winner, a smash, but can you honestly say it's valid after the sonic and artistic excellence of his previous works?"
Er.....I don't think the reviewer liked it.
Before anything can be improved, it needs to be measured first.