It is impossible for anybody to offer up more than a guess ... so here is my guess:
ignoring the high probability of a poor quality recording pressing , then its likely your cdp that needs significant upgrading to match up to the performance quality of your integrated amp . Everything is built to its pricepoint and the Marantz is only a $500 spinner .... you only get what you pay .
the following review view says it all as its prevailing wart:
https://www.whathifi.com/marantz/cd6006/review
"....Favours easy listening over out-and-out detail....
ignoring the high probability of a poor quality recording pressing , then its likely your cdp that needs significant upgrading to match up to the performance quality of your integrated amp . Everything is built to its pricepoint and the Marantz is only a $500 spinner .... you only get what you pay .
the following review view says it all as its prevailing wart:
https://www.whathifi.com/marantz/cd6006/review
"....Favours easy listening over out-and-out detail....

