Many thanks for that Howard. I'm not sure if my ears can tell the difference, but I'll do some tests. I had bought some Martin Carthy MP3s and later got a present of his boxed collection, so there are some tracks I have in both formats. I also buy CDs and just added Harry Cox's double Cd to my collection and again can do a comparison there. However, as I am interested in learning songs rather than having a state of the art sound system, I think the quality is O'K.
Regardless of what format I use, herself stills says" Can you not turn that Down"
                                     Zozimus