PDF to PDF/A Color Conversion Issue

Q: We have an issue when we are converting a PDF file to PDF/A1b.
The resulting PDF/A is a few shades lighter than the original PDF.
The problem appears to be the colour space that is added to the page
resources. If I remove this colour space manually from the PDF, the
PDF looks the same as the original.

Here is an example of how we are performing the conversion:

PDFACompliance pdfa = null;

pdfa = new PDFACompliance(true, inputPath, inputPassword,
PDFACompliance.Conformance.e_Level1B, null, 256, false);
pdfa.SaveAs(outputPath, IsLinearized());

I have attached the files:
Input.pdf - is the original file.
Output.pdf - is the file after conversion. The PDF is lighter
that the original.
Output with Color Space Removed.pdf - is the output file, after I
manually removed the colour space. The PDF looks the same as the
input PDF.

Can you let us know if there is something that we can set on our end
to prevent this?
A: Because the input file is not color calibrated, PDFNet (or PDF/A
Manager) embeds a default color profile which may differ from the
default profile selected in a PDF reader (in this case PDF will render
differently depending on the preferences used for color management in
a specific PDF viewer). Instead of erasing the color profile, you
could simply replace the profile with another ICC profile, but keep in
mind that the user can alsways chnage the default color profile.