Apparently the Si9132 chip in the PS3 cannot transmit TrueHD/DTS-HDMA bitstream and its pair released at the same time - the Si9133 chip - cannot receive it. Note that PS3 may at some point be able to decode DTS-HDMA to PCM, but there are no plans for this announced at this time.
Silicon Image has released two new chips that support passing of nextgen audio codecs bitstream via HDMI 1.3 - the Si9134 (for players) and Si9135 (for receivers).
And no, I don't know what HDMI chipset the BDP-S300 uses nor do I know which one the HD-XA2 uses. Although, Toshiba seems to have gone with Broadcom over SI so they are probably using one of Broadcom's HDMI solutions.