J
If I have read it correctly you are looking to sell various components of a Beosystem 5500. Your target audience is probably people that aleady have a Beosystem that are looking to replace an individual component, As that is quite a specific audience you may have more luck with the greater pool of people that are out there on ebay.
If you list the items on ebay they will certainly sell, you may just get a little less than you are looking for as a completed items search suggests that the prices you are asking appear to be a little higher than items in comparable condition usually fetch on ebay, which might be another reason for the lack of responses.
It would be a tragic waste to skip them!
Simon