Recently, we had a customer e-mail us with the following problem.
He had made some icons in Adobe Illustrator and exported them to Altia Design, but they did not look good. Since Adobe Illustrator can create .dxf files, he tried to use the Import DXF feature in Design. But when he tried to import a .dxf file created by Illustrator, it did not work.
Altia's DXF import function is somewhat limited and is intended more for importing legacy AutoCAD .dxf files. Many modern features are not currently supported. For more specific information, refer to section 3.9, "Import > DXF File..." in the Altia User's Guide.
Your best bet is to export your Adobe Illustrator icons as higher resolution PNG files. When you do an export from Illustrator, try 150 or 300 ppi (pixels per inch) on the PNG Options dialog. You can also import your Illustrator art into Photoshop, where you have much more control over the image size and export options.