Pro-ject speedbox: Is improvement worth the $ ?

Not really, Brf said it best. You will be better off putting the money on a better cart.

Which Graham Slee are you getting Devilboy? We may be able to recommend a cart based on the Slee's specs.

Well said Zd542!
Stop spending and start listening!
Your Slee is far better than any entry level phono preamp usually paired with your current analog set up(2.2LE and 2M Blue) Good! You will get the most out of it.

At one point I was "up there" spending lots of $$$$ with the likes of Linn, Conrad Johnson, Audio Research, JennaLabs, Spendor, etc.

Now I'm back "down to earth" (less money, more synergy) with a system that I love to listen to for hours!!!

There is plenty of great stuff out there at an extremely affordable price. Don't get carried away with the "advertisement syndrome" and trust your ears!

Happy listening!