Your problem is quite simple to solve. Just drag a "Clear" patch into your workspace at the highest level, and set the rendering layer to 1. This should prevent your gradient from overlapping with your cube. Also, note that the "Virtual Splitter" patch is not necessary. You can simply drag the image output to all the sides of the cube. However, if you decide to keep it, I would recommend to change the type to image from the setting menu in the inspector. It's never recommended to use virtual, unless you really need to, like say you want to forward a number value to a boolean or index input.
Hope this helped. I've just signed up on this forum to answer your question. I'm a Quartz Composer addict, and I love helping people.
I'm also a member of the Macosxhints forums, and looks alot like it, they just use a different color scheme.
If you have any other questions, feel free to ask.
On an unrelated note, the musical note image you're using seemed very familiar at first. After doing a quick check, I realized that's the exact same image I included in my "Explosive Reflected" screen saver since the first version
I'm not mad or anything, on the contrary, I'm delighted that you are one of the 1000 or so people to have downloaded my screen saver

All the images are free to use to everyone, for anything. I just thought it was really cool to see someone actually use it.
In fact the image was created with one of the Photoshop basic shapes, in about 30 seconds, when I was just creating random patterns for people to use

If you need help with anything else, I'll try my best to help ya
Best regards,
~Felix MC
