Sunderland face Luton in the Carling Cup and Irishman Murphy told The Journal: "It just gave me a rough idea of what it was like and what it would be like for me second time around when I came back over.
"It wasn't a great experience but it helped me.
"I think when I went back home it was the best thing I ever did, to be honest. I played regularly, was happy to be playing, happy to be home and just really happy to get a second chance at it.
"I always thought I would get another chance and I was determined I would take it this time. Thankfully I have.
"I knew I needed to establish myself in the first team at Sunderland and I knew it would take a while settling into the pace, the demands of the game over here. It took me a while to settle in but after I did it was a dream come true really - the facilities, crowds, stadiums, everything about it is all you ever wanted as a player."