Panasonic SA-XR70 or SA-XR50? Which One?

What is the difference between these two receivers. I will be using it with a high definition TV with high def cable service, if that matters. Thanks.
I am looking at these for a "backup system". The biggest difference is in the addition of ProLogic X (quasi 6.1) and the very cool feature of running this as a digitally biamped stereo receiver with digital crossovers. This has come as a direct result of some fringe audiophile group that has embraced the xr 45 and purchased digital pro crossovers to do the same.

In addition, the 70 has HDMI connectivity which is the latest and greatest (subject to change) digital connection for both audio and video in one. If you don't have at least a dvd with this output or a monitor with this input it won't do you any good. I have listened to this setup and it is very good price not with standing. When you take into consideration that the xr 45 was $300 and the x-over was $500, the sound is absolutely fabulous!

The digital amps in the XR 50 and 70 are third generation and have a much higher bandwidth and are almost 6x quieter. My guess is that in the next 3-5 years we will see many more digital products on the market. Sharp had/has a very highly regarded digital amp ($12k) even amoung the "hair shirt" audiofools.

At any rate I am going for the 70 and will be comparing it to my stereo only system that consists of a Bryston B60 biamped with the 3B-ST utilizing the Bryston 10B as a crossover all powering a pair of Focal Aria 5W's. This system retailed at $8200 with interconnects.

It may sound crazy but the sound I heard from that xr 45 with digital crossovers biamping a pair of Theil 2.6's was nothing short of amazing. Good luck!
Thanks for the info.
The digital amp on these Pannys is a huge over-achievers. I've been using the XR50 for about 4 months. Now, I am using them to drive Maggy MMGs. The two make an incredible combination, very DETAILED and dynamic.

BUT the imaging is awesome.

My MMGs straddle my fireplace therefore the system images the performers holographically inside my fireplace.

Don't underestimate the performance of Panasonic's current crop of digital amps.
I just sold my Marantz 8200 after getting a JVC RX-F10 that's $250 to play with. The digitals are pretty amazing. And I thought the Sony 9000ES was the top digital; a $12K Sharp! My main problem with it is I keep looking at the CDP to make sure I hit play as there is zero background noise.
HDMI may not be so great for those that want to squeeze all the performance they can out of their equipment. It is great for the average Joe to have one cord hook up.