When you did the self-calibration, it should ( the new .icm ) appear as a new selection for that paper. The adobe RGB source profile is the preferred source profile, so that should be selected, not sRGB. I do not have that printer, but I am familiar with large format HP's. In Acrobat, you should select "let Printer Determine Color"; so your second setup in your post is correct. Confirm that you have "Leave Color Unchanged" selected in Acrobat settings. That printer has an Accessory RIP ( Efi Designer Edition ) for $795. I would definitely use that for more accurate color...well worth the investment.
The files I get from my clients are all PPT slides. I don't know how (or if) PowerPoint manages color. But I assume they are sRGB. I save the PPT as PDF and open to print from Acrobat. I do not see a method in Acrobat or Preflight to Assign or Convert Profile (like in Photoshop) to ARGB.
But still, I wonder why I do not get a choice in the HP driver to select anything other than Adobe RGB - no matter what the image being printed is tagged. (I've tested this printing from Photoshop, where I'm more familiar with CM - the HP driver stays stuck on Adobe RGB as source space.)
So far, the best results I get is to go PPT to PDF to Adobe Illustrator and print to the HP z2100 with Illustrator handling color. A pretty convoluted route. A RIP would be nice, but probably not in our budget for the limited posters we see a year.
Acrobat Preferences can be edited to "Preserve Embedded Profile" or "Ask When Opening" from .tiff; since there are no choices for .ppt files conversions, Acrobat is probably maintaining the sRGB from Powerpoint or is not applying any color management in the PDF, so Illustrator is left with the job of converting upon opening the file. I'd like to know what your Illustrator Color Settings are. There is a big misconception out there that sRGB has a larger color gamut than Adobe RGB. In print, the preferred RGB profile is Adobe RGB because of its larger color gamut and its ability to map better to CMYK. In inkjet, certain inkjet printers may have a larger color gamut than other inkjet printers, especially if they use addtional color catridges like the Z2100. If the driver is limiting you to Adobe RGB, then there may be some information not installed. Check your installer disk for other RGB profiles. Since you are limited to Adobe RGB, then you should refer to Illustrator's Color Settings. You may have to do some tests and experiment with a few different scenarios out of Illustrator and its Print dialogs. A RIP may not be necessary since you are working with RGB files, so Illustrator might be better using an RGB color space. Let's assume Acrobat has not converted to Adobe RGB and has no color management applied. In Illustrator, set the RGB color setting to "Ask When Opening" and set the work space to Adobe RGB. Open a PDF from Acrobat converted from PPT. Illustrator should ask you, when opening the file, what RGB profile do you want to use ( assigned or working ). Select working RGB ( which is Adobe RGB ). Send that to Print and see what happens. Do this for every RGB setting available in Illustrator's Color Settings "Working" space ( i.e., Colormatch RGB, sRGB, etc. ). Assuming your monitor is calibrated and supplies you with fairly accurate color representations, see which print matches the original PPT the closest and set that as your workflow for similar projects.