I would be very surprised indeed if the USB cable between the BDP-1 and the hard drive would make any difference whatsoever.
Between computer and USB DAC, I can suspend disbelief and imagine that if there might be a difference between good and reliable SPDIF cables versus high priced SPDIF cables, then I might imagine that there may be a difference with USB cables between computer and DAC.
But between computer and hard drive? No way unless you have a faulty USB cable.
You have to keep in mind that between computer and USB DAC, the signaling between the two is either an isochronous or an asynchronous data stream. If there is error or re-transmission is required, the data is not corrected. But between a computer (or BDP-1) and hard drive, the hard drive is treated as a mass storage block device -- error and re-transmission is always retried, and data blocks are buffered into the filesystem cache of the operating system.