[4candles]

Reading the PDF about the RDR-GX300, the specifications (page 88) only list "Dolby Digital/2 ch, 256kbps" in the recording audio formats - so the answer to your original question appears to be no, that particular DVD recorder can't record PCM audio.

But I'm assuming that you are looking for a way to create the best possible DVD (because you are asking about LPCM audio), in which case, I would suggest that you try and avoid using a standalone recorder. Once the video and audio are inside a computer, they should stay there, and PC software should be used to author the DVD for burning using a PC DVD recorder.

Otherwise, you are introducing unneccessary analogue stages in both the video and the audio. You shouldn't have any problem authoring a DVD with PCM audio using PC software.