Hi Folks , I've been a bit of a lurker here for the past few months, researching my 606 purchase. I've read a number of posts about the 50hz (in ireland here) ground/earth humming problem, which may or may not be related to a mis communicated buzzing problem. Well, I bit the bullet and have been living with the 606 for about a month now, I just though it might be usefull to share some things i've learned about this amp. Up untill very recently I've had lots of analogue connections made to this amp. (didn't have a hdtv so was outputting video over composite, shocking I know!) I had ps3 and wii input via composite video and stereo RCA audio. dvd player was scart to tv and spdif to onkyo. I had the 50hz hum and badly, I put this down to all the crappy analogue rca connections, this assumption was reinforced by a quick test: removed some rca connections and hum reduces. I now have only hdmi connections to the amp and it's probably in it's final configuration, so here goes: 1.If you have 5.1 speakers the audussey setup will not run if you have connected your rear speakers to the rear/back surround channels. 2. Audussey sets my center and sub too low (for my ears anyway) and my surrounds too high. 3. The onkyo runs quite hot, but this has not caused any problems. 4. The amps setup menu will only display on the screen over hdmi. 5. If I use anything BUT a sole optical connection from ps3 to onkyo, (hdmi,analogue rca) The xmb screen on the ps3 will result in a 50hz hum through my speakers. it can be heard on quite low levels of volume (as low as 20). 6. Turning off dynamic eq will reduce the hum significantly, but NOT fully. 7. Turning off audussey eq will also reduce the hum. 8. I eliminated all analogue connections to my amp and the hum remained. 9. upon disconnecting the ps3's hdmi input the hum dissapears completely. 10. The hum is still apparent with the ps3 off (still plugged in) with hdmi connection. 11. Hum gone completely when ps3 is physicaly disconnected form wall/pugboard/extension lead. 12. This in my view is a classic earth/ground loop problem, the issue is the ps3 has an earth connection made in it's plug. the onkyo only has live and neutral made, via a 2 pin to 3pin adaptor. By the look of the onkyo power lead I suspect it only contains these 2 wires, it's kind of thin and flat. Now the onkyo amp contains lots of high voltage transformers/amplifiers etc and has a metal case. The ps3 is probably mostly runing off 5/12v dc and has plastic case. Q.1 Why is it ok to have no earth connection on the onkyo when the ps3 needs it? 13. I disconnected the earth in the ps3's plug and lo and behold, no hum whatsoever even at max volume, only pure beautiful silence! I know this is a classic dumb ass thing to do. Q.2 Can anyone offer me any inexpensive alternative?