Actually, I'm now using a USB interface to link them together as the AE inserted a delay in when starting playback. Very annoying.
Also, sorry for any misunderstandings in my original post - the 4-second buffer is neccesary to bring the DAC64 up to the level of the Blu. Without the buffer, it sounds thin.
It's also worth noting that the Blu has a dual output that I did not try. I've heard from my dealer that this once again takes the Blu to a different level as it seems to split the signal or something and the DAC64 has circuitry to reassemble it. I'm still ecstatic with my system.
I just bought an Audio Research DAC-5 and might just give the AE another chance in that context.
Graham