sRGB color values not exported correctly on PDF export

Thinking this is NOT an issue of typical missing Color Management know-how, but maybe really a failure in CorelDraw RGB pdf export(!?), because whatever I am trying to set (CM off, CM sRGB, etc. etc. etc. ...), and also pdf export settings: 

When I export vector graphics to RGB/sRGB and open the pdf in another software (like Serif Page Plus, Adobe etc.), the color values are variying a little bit.

For example, my gray value of a logotype in Corel was 118, 115, 113. 

Now I export as pdf (many logical!! setting of CM tried!!!), any other software that opens the document - also CORRECT CM settings - values are 117, 115, 112. --- The same light variations nearly anytime with any RGB color. Not possible to create vector pdfs of logos for my clients correctly this way! Really bad. 

Instead of starting a discussion about Color Management Settings, could any professional, maybe a Corel member check this behaviour in practice and give me a feed-back!? - In the best case let me know the complete settings for Corel CM and pdf Export to get the RGB pdf export done correctly. 

Thank you so much!

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(I am currently using X4, but know that same behaviour from X3 and passed again hours to try really all reasonable CM and export combinations, at least I think so. Windows7 and WindowsXP)