Sony 5400 question

Can I use the sony to play sacd's as I normaly do and have the digital out connected to a dac and use as a transport. That way I can still play my sacd's and incorporate maybe a benchmark w/usb for better redbook playback and also get into computer stored hi res files via usb?
Yes you can.
Thats exactly how I've hooked up my SCD333es player to my Benchmark USB DAC. I did have to procure a switch box for the SACD out, as I have run out of inputs on my pre-amp. By the way,I do like the sound of the Benchmark. It is a wonderfull piece of equipment.
Good luck, John
It will be interesting to compare the XA5400ES with the Benchmark, because the Sony unaided by a separate DAC seems excellent with redbook.

The coaxial Digital Output (SPDIF) of the Sony SCD-XA5400ES will only output the CD layer of the SACD being reproduced, not the hi rez of SACD. You won´t get any digital out when playing the SACD layer. Another thing is the HDMI output, but that´s another story (I would like to try HDMI output to Atlona HD577 which strips the hi rez; in this case, the Sony would need to send PCM thru HDMI).