The BDP-1 uses USB to bring data from an external drive to the internal memory for reformatting and passing on the DAC. USB 1 Full Speed does not quite have the throughput (12 MBps) to handle high resolution files. USB 2 High Speed has a throughput of 480 Mbps which is more than ten times what is necessary to handle high resolution files. USB3 can pass even more data (3 Gbps) but brings requirements and system overhead that will not improve the sound and will increase the power requirements. USB3 extends from a PCI express interface which is not present or supported with the processor we use. Changing over to a system board that would support USB3 brings heat problems, requirements for a much larger power supply and a number of other aspects which will change the product completely but not improve the audio chain and can potentially degrade it.
Drives have SATA interfaces. External drives use internal hardware to convert them to USB, Firewire or eSATA. While it may make a difference loading data onto the drive, for playback the throughput requirements are much lower so the interface won’t change the playback properties.
James