The newer versions of this receiver have this feature. Some members have indicated that the box displays a sticker or marking providing the PLIIx designation.
When I bought mine it had: - a sticker on the box mentioning it was upgraded for DPLIIx - a sticker on the front panel of the AVR indicating DPLIIx capability - an insert in my owner's manual for DPLIIx
So basically, if the RX-V2400 you purchase was upgraded for DPLIIx, there's no way you can miss the mention of it. If all 3 of these elements are missing, it was most likely not upgraded by Yamaha for DPLIIx.
Hey I just bought this receiver yesterday in Temple TX and there is nothing about DPL anything on the box. What am I missing if it doesn't have it? How do I get it upgraded to my system if I want it? I assume I'll have to go back to the dealer...
if I was you I'd return it and get another one WITH the upgrade in it already. Mine came with all three items MuneebM says and It rocks! If you can't do that (I doubt it) then bring it back to the dealer, he'll send it back to Yamaha for the free upgrade.