Digital BW, The Print

I've been playing since one week now with my new set of UT-R2 inks 
(warm) for R220. First impression is very good. I like a lot the 
warm tones and the possibility of changing them using different 
papers and also working with BO (much colder).

Now I'm checking linearity printing the typical 21-tone bar, and how 
this linearity is influenced by the different driver and Photoshop 
parameters, using also different ICC profiles from Paul's web site, 
just to try.

The first problem I've noticed is that the black color (code = 0) 
does not print as deep using Photoshop as it prints using QTR. The 
most surprising thing is that the black darkness seems to not depend 
at all on the printing parameters.

In the Epson driver, I've played with the paper type, gamma (2.2 and 
1.8), and with the color setting (standard, Adobe and ICC=OFF). In 
Photoshop, I've played with the color management (colors determined 
either by printer or by Photoshop, with the mentioned ICC profiles).

All these parameters affect clearly to the dark and mid tones, but 
the black color (code = 0) is always the same: not as dark as the 
black I obtain from QTR.

I've printed from other programs that use the Epson driver and the 
results are the same, so Photoshop does not seem to be causing this.
Could the Epson driver be limiting the load of black ink deposited 
in the paper, or converting for some reason the code 0 to a higher 
code?

I've checked also for the possible oscillations described by Paul 
when fine tuning  D-max, printing a 6 tone bar from L going to 0% to 
5% in steps of 1%, but there is not an appreciable difference 
between them, while the QTR black is clearly darker.

One could think that the d-max of the paper is causing this, but QTR 
gives a deeper black in the same paper. For money reasons, I've 
doing these tests with Illford smooth multi-use matte paper.

Sure I'm doing something wrong. Any help will be appreciated,
thanks,

Fernando