Anthem Pre-1P... how good is it?

I've an Anthem Pre-1P and am thinking about getting something else for a phono stage. I've only been able to compare it to a Project Tube Box, which the Anthem seemed to sound better. I'm wondering if anyone has an opionion about this Anthem phono stage and how much up the phono stage food chain I'd have to go to get a noticable difference. When you look at the guts of the Anthem, there doesn't seem to be much there besides the two pairs of tubes. Has anyone also had the Anthem upgraded/modified by Parts Connextion and if so was it worth while... could you 'hear' an improvement.
Thanks
Ben