I am looking for a decent amp to drive a pair of wharfedale 7.1* speakers (gale stands) before i upgrade to some cresta 2/3s. Can't cost more than £150. Source will be a sb live 5.1 computer sound card, again until i can afford to upgrade. I was looking at the Marantz pm4200 or the Cambridge audio A5. Are there any others that are worth considering? I notice everyone seems keen on nad amps but they seem out of my price range.