Did it sound "full" before you got your hands on it?
If not, then it's more likely that it's the clients fault.
If yes, then it's yours.
Your an engineer, not an alchemist.

There are lots of tricks to widen stereo images, waves makes one. As well you can alsways try MS the old fashion way.

First guess?

Upgrade your soundcard/interface.

The secret recipe for mastering is a combination of both Digital & analog processing devices. You go out of the digital realm and back into the digital realm. Taking a few side trips along the way. So it ain't all done with blah blah software. It takes a highly experienced & skilled individual to know which pieces of digital & analog to mix & match and where to output signal chain to do so. So maybe you should hire a really good top-notch mastering engineer? Pay them extra to be present during the mastering session & learn what you need to learn. A lot cheaper than school. And a lot more practical.

The great mastering engineers still use a boatload of analog equipment. What's that tell you?
Ms. Remy Ann David

That that's the way they learned.... give it a few years it should be intereseting. Maybe mastering will degrade further. ;)

Link555 wrote: That that's the way they learned.... give it a few years it should be interesting. Maybe mastering will degrade further. ;)

lol :P