James,
Transferring a file: (i.e. no jitter is involved, it's just data)
HDD to Digital Player/computer: Thunderbolt, USB3, eSATA, FW800, FW400, USB2 (sorted by speed)
Playback of digital music stream (i.e. jitter is involved, it's a PCM stream):
PCM/DSD to DAC: I2S, AES/EBU, BNC, COAX, Optical (sorted by general recommendations, ymmv)
Playback of digital music stream with USB/FW DACs:
USB DAC: USB3, USB2, USB (sorted by speed)... USB3 has more error checking than USB2 and 1.
FW DAC: FW800, FW400 (sorted by speed)
For BDP-1 today:
Disk Drive -> USB2.0 -> BDP-1 -> AES/EBU -> BDA-1
100Mbit Etherenet -> cat5e -> BDP-1 -> USB2.0 -> Hard Drive
For BDP-2 tomorrow:
Disk Drive -> USB3.0/eSATA -> BDP-2 -> AES/EBU -> BDA-2 (same as BDP/BDA-1 approach)
Gigabit Ethernet -> cat6 -> BDP-2 -> USB3.0/eSATA -> Hard Drive (file transfers are ~10x faster)
Possible improvements.
Disk Drive -> USB3.0/eSATA -> BDP-2 -> I2S -> BDA-2 (possible improvement in jitter)
Gigabit Ethernet -> cat6 -> BDP-2 -> USB3.0/eSATA -> Hard Drive (file transfers are ~10x faster)
I have zero interest in using a FW/USB DAC since they add one more level of complexity, would rather see the BDP-2 just provide the I2S output.
Disk Drive -> USB3.0/eSATA -> BDP-2 -> USB2.0 -> USB Controller -> S/PDIF or I2S -> DAC
Jim