EPKowa pips-scx6500_6600s-2.6.2

[redwood]

I've installed Epson's EPKowa drivers following the thread:
https://forums.gentoo.org/viewtopic-t-43648-view-next.html?sid=754d4a2ec4b3604532d55d05cfc1f462

but I can't seem to print:

# /usr/sbin/lpadmin -p scx6600 -E -v ekplp:/var/eklpd/ekplp0 -m ekscx6500_6600s.ppd

# ls | enscript -B -M Letter -f Courier18 -p - | lpr -P scx6600
[ 1 pages * 1 copy ] left in -
lpr: Unsupported format 'application/postscript'!

I also get the same error message when trying to print a test page from the cups admin utility
https://localhost:631/printers/EPSON_CX6600?op=print-test-page

I'm currently using the
CUPS + Epson Stylus CX6600 Foomatic/gutenprint-ijs.5.1
driver with this CX6600 OK.
I just wanted to compare the quality of the photo print between the different drivers.