Yes it would appear that you have the latest 506 firmware. It will only help when I can get someone from Pioneer to confirm what each revision fixes.
A trawl through a very long thread over on AVSForum essentially brings out the following information...
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Pioneer has not been forthcoming in letting anyone know what each firmware update does. It appears that 406 fixes the Y/C delay at least. Unknown what 506 does. The only way to upgrade is to send the unit to Pioneer.
Someone surmised that 516 was identical to 506, except that 506 is region 1, and 516 is another region. 526 could just be yet a different region. ??
Firmware upgrades relate to playback issues with some DVD audio due to the new music copywright act. The upgrade is NOT to improve the unit as the issue is not with the player but with a specific disc. If your unit (DV59AVi) is not having playback issues with a specific disc, then you do not need a firmware upgrade and the version you have (1.406) is the latest for that model
I will also report, I have the 406 firmware and perfect Y/C delay according to Avia. So if people are wondering if 506 was the only firmware to have this fix, I can report it is not.
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I'm hoping that this indicates that the 406 firmware which I have is suitable enough for trouble free HDMI playback.
You can have a look at the thread yourselves at...
http://www.avsforum.com/avs-vb/showt...&highlight=868
If you do have alook and can glean anything else from it then let me know.
Keith