In that case you should have really bought the DV79 or DV29, the video performance through the HDMI connection is superior to that from the component output from the DV78. The only Arcam machine that would give either of these a run for their money over component would be the now discontinued DV27A.
I don't mean to pry but it would appear you have purchased this product on price alone, are you at all willing to divulge which retailer sold you a DV78 at £499 without first investigating your current situation and the equipment you planned to use it with. As part of good customer service I pride myself on finding the best product for the customer's needs regardless of price or what I have lots of in stock and need to get rid of. It would appear that the retailer you purchased from did not pay as much attention to detail or you purchased without advice.