Is upgrading worth it?

Choose upgrades that make your music more enjoyable to you, not less. It can be done.

Odd. If you like the 1970 Marantz receiver sound.. Why bother to upgrade?
I find i love the increased clarity my nwer additions have given me, for all recordings...
I accept the limitations of old recordings..
In fact i am again listening to 1940's Jazz... Wonderful, limitations and all.

Digepex brings up a major problem for a lot music audiophiles like. It can be very frustrating investing a ton of money in your system only to have a lot of your favorite music sound worse. There are brands however that can put some life and air into recordings that sound flat, lifeless and dull on many highend equipment. Just have to search that stuff out.

The trick I think to upgrading is understanding what you want or expect out of an upgrade sound wise. Balance is also important and can easily get lost in the shuffle if one focuses too much on any one element at the expense of the whole, example- soundstage or ultimate detail or dynamics. These can all exist in one system but takes a lot of careful thought and matching and not a small amount of $$$. Get comfortable with your system as it is and try replacing (or demoing) one piece or equipment change at a time to ensure you like the difference it makes without overly impacting the things you already liked. If you really dig the 70's Marantz sound, you may try a foray into the McIntosh world.

It would be very helpful if we were to know your system details, room parameters, and musical preferences.