Thanks for your insights:Chris,Dan, Grover, Jason and Tom.
I gather that chipsets have closed the gap with internal cards which still have an edge. My 6 month old laptop which runs i5 mps.came with Realtek which I don't like. I will look at external sound cards as an alternative though I know the old saying."a system is no better than it's weakest link". I owe that to my AudioBytes.