Hi, I'm looking at getting a AV amp, and I'm new to this. I see the Yamaha just got the what hifi award for 2012, but it's £500. Ive been recommended the Onkyo TXNR 515 as well, which is £330. What is the difference in the sound quality? I can see the difference in the specs, but what about quality of sound, is it worth the extra £170 to buy the Yamaha?