said by Guspaz:
To most consumers, the difference in quality between even AC3 and lossless is indistinguishable. For those with both a high-end home theatre system and a discerning ear, higher-end blu-ray rips often include lossless audio, although these rips are often not much smaller than the original blu-ray themselves.
All my rips have their audio transcoded to 640Kbps 5.1 AC3 in an H.264 MP4 container. Even though DTS-MA and TrueHD aren't supported in an MP4 container, I cannot tell a difference anyway.
Of course, I don't have a high-end surround sound system either, due to neighbors.