I was not able to buy from ABT because I do not live in the Chicago area.
Afer a LOT of searching, I bought my RX-V2400 from Buy Rite Electronics
http://www.BuyRiteElectronics.com ] . They only had about 10 reviews on resellerratings.com, but all were "Very Satisfied." I had found them in an eBay search for the 2400. Their web site itself did not show the RX-V2400. I emailed them at
[email protected] to ask if theirs had the DPLIIx. They answered:
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Thank you for your email. The YAMAHA RXV2400 RECEIVER is in stock and can be shipped out immediately. The model we have in stock comes with Dolby Digital ProLogic IIx. If you have any more questions or wish to order this item then please call Customer Service toll free at 877.328.9748.
Your business is much appreciated.
Thank You,
Amanda
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After thinking about it for another day, I called the above number and got Tony, who took my order. I might add that my experience with him was friendlier than my typical experience with a NYC area dealer.

The total, including s/h, was 10c less than seven fifty. I ordered it on a Thu afternoon and rec'd it (in Arkansas) the next Thu. It was not double-boxed, but the Yamaha box was completely wrapped in brown paper. To my great relief, the box said it had the DPLIIx (there was a supplemental manual inside, too).
As far as I know, BuyRite is NOT an authorized Yamaha dealer, but I was able to save a considerable amount from the MSRP. So far, so good!
HTH,
Jim