Assuming both amps are in good servicable condition then I doubt you'll get an improvement with the 2400. I have owned both, and rate the Beomaster 5000 amp very highly. The 2400 is ok, but not as powerful nor does it sound as sweet as the 5000. I had my 5000 with a Cona and some CX50s and was very satisfied with it :)

Thank you, John. I am now listening through beomaster 5000 (sometimes beomaster 7000) but I am not satisfied at all.  Maybe, I will put it in kitchen. Because in sitting room I am using Beomaster 8000 + Beovox MS150, and in other room is Penta + System 7000.

Not too surprised! The MS150 is one of the best speakers that B&O made and the Pentas are not bad either. CX100s are link room speakers and in my view are struggling to be defined as Hi-Fi. They make a pleasant sound - I use a pair regularly - and a Cona does add some of what is missing, but any good pair of speakers will obviously outperform them. I would put them in the kitchen - small and they wipe clean!