Hi Gar,
Just a quick comment, when you choose "Photoshop Manages Colors", did you also set the printer's settings to "Not manage colors"? (printer must be aware that does not have to do any color conversion as the data comes ready from photoshop)
Yes, I did turn off the printer's settings to "Not Manage Colors."
There is no profile for canvas with the 4880 printer driver even though Epson sells rolls of 17" wide canvas for this printer. Epson does have a canvas profile for the 7880, 9880, 7900 and 9900. Good show Epson! Epson recommends choosing either "Water Color Radiant White MK or PK" in the dialogue box.
All my files are from scanned transparencies that were given to me. They are untagged RGB, and I don't know, and can't find out, if they were modified in sRGB or aRGB, or if that makes a difference.
The 4880 is a great printer. I will try to do some experimentation today.
Gar