I took the plunge and snagged the Onkyo nr626 from A4L. Been messing around for the past few days and think I've finally got it down. The Marvell Qdeo upscaling indeed impressive. It has finally resulted in a similar image to my old 4:3 480i trinitron with DMR-es25 in many ways, whilst also still highlighting the format's inherent defects. You can't ever have everything right?
Also running the es25 makes everything simultaneously better and worse. Go figure.
But here's the weird thing. The sound is off when playing LD. Sure I took a big leap in clarity and power etc. and my speakers aren't the greatest, but no mode so far seems to replicate plain DPL on my old Sony str-de675. Some films are worse than others, but both DPL2 and Neo 6 are all over the place and send sound to all different channels. The closest is Onkyos proprietary mode DPL2 Theater dimensional but it isn't perfect either.
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I did the Audyssey setup with antenna and finally realized to turn off all the EQ and audyssey curves etc. That helped quite a bit, but I'm still not getting the simple punch and DPL effect of my old amp.
Any suggestions?