I'm not familiar enough with the XA2 to know the underlying issue here, so my comments may not be terribly useful. Panasonic had an issue with this on their BD30 player relating to the HDMI output, and they fixed it with a firmware udpate.

Boosting the LFE channel via analog is problematic - especially since not all players require that boost, so you have to provide a manual control of some sort. The 970 doesn't offer this, and I doubt a future Outlaw processor would, either.

Here's another thought to toss out, which might be of use: the 970 offers analog bass management for the 7.1 Direct input. By setting the speakers to "large" in the XA2, you only output LFE via the XA2's sub analog output. You can trim that channel up in the XA2's setup (assuming such a control is available - as I said, I'm not terribly familiar with the XA2) and engage the 970's 80Hz analog crossover. Redirected bass will be at the correct level because it's handled by the 970's crossover network, and the LFE channel will be boosted internally to the XA2.