What is a toroidal transformer, and what benefits does it provide? I notice that one some receivers and amps, they say that they have toroidal transformers, I've seen pictures of them, but what makes them good? I own an Onkyo 797 and my transformer is in a big silver box that was about the size of the one in a Denon 3802, but larger than anything else in it's class. Also about the power supply capacitors, what are they for? My 797 has Nichicon, the same brand as the 989, are those good? Any input would be great, I'm just curious.