If your player can seperate PCM vs Bitstream on DD/DTS vs TrueHD/DTS MA then according to mark either Bitstream or PCM should work with the HD621 and would be great way to compare how much the apodizing upsampler in HD621 helps over the processor decoding. Try it both ways.

If your player does seperate the option I'm curious what player you have.

On PS3 once you tell it to send PCM over HDMI it ignores all other options.

- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
HT: G61RSL, 4x5K, 5.5KHC, 2xSC6000, Transporter, HD621, Philips BDP7501 4K, Tivo, 65" LG OLED 4K C6
Computer: Foobar2000, 5K, Mojo, HiFiMan HE1000 V2