Hi Mike, thanks for your reply. My scanner is an Epson V700, it's a rather high-end photo scanner and shouldn't represent a problem, unless misconfigured. I've followed all the instructions about 48bit scanning and driver setup. There may be other scanner related issues?
I'm stucked on the 8-9% figure on both glossy and semimatt paper. Both the paper types are not from a well known brand name. I would say I've reached the peak performance from the ink-paper pairs, but something tells me that there's still something I've not considered yet. Moreover I'm fairly sure I saw a 16% coverage some time ago, while testing those same papers, but unfortunately I forgot to note the parameters I was using.
Thanks again for your help
Alessandro