Originally Posted by emptychair
That will depend on whether or not your receiver allows for separate digital and analog settings for your subwoofer. If it does then calibrate your sub separately for each input. If your sub setting is global then you will end up getting more bass via digital.
What??? I'm sorry, but this response makes no sense, on several levels.
The 'amount' of LFE is determined by the levels you set during calibration, and has absolutely nothing to do with the transmission method. You can calibrate your system for any source, and the XA2 has its own level settings; the fact that you may have global-only settings on the AVR does NOT mean that you can't get the levels balanced properly - it just makes it a bit more tedious.
The 'quality' of the final signal is determined by the type of DACs and the bit depth and sample rate.
1) If you use the analogs from the XA2, you are getting the full bit depth and rate from the lossless codecs, and you have a set of very high-quality DACs.
2) If you use the SPDIF digital, you are getting down-res'd digital, so you do NOT get the full bit depth and rate of the lossless codecs. You are also now using the DACs in the AVR, which may or may not be as good as those in the XA2.
3) If you can use bitstream decoding with HDMI into an AVR that can decode TrueHD, you might be better off with this than with the analogs, but only if the DACs in the AVR are better than those in the XA2.