Sony HAP- Z1 ES music server into a DAC... is it possible?

My pal with the Sony server would like to add a fine DAC to his system.  Is it possible to digitally stream music out of the Sony unit into a DAC and then into his preamp?   I can't figure if the Sony has that capability.  If it does, what is the means of the the digital output?  Thanks for your insights.  
With the latest firmware upgrade, the Sony can be used with a different dac.  You would use the usb output.  I tried it with a Wyred4Sound dac2 dsd  se dac and preferred the Sony internal dac better. 
Thanks for the insight.  BTW, have you ever heard a different DAC with the Sony or are you content with its internal DAC?   
Just a note about it, not all DACs are compatible with the Sony. Obviously it requires a DAC with a USB input but there are reports of some DACs not working, and it seems to involve a compatibility issue with the DAC's USB receiver circuitry. You should try a specific DAC in combination with the Sony to first see if it works and second to see if it offers any sonic improvement, since the Sony's internal DAC is no slouch and can outperform many external DACs.
The update to make the Sony HAPs work with external DACs has been out almost two years
My pal with the Sony unit is wondering if the addition of a Ayre QB-9 DAC might be a sonic improvement.   I have one for him to try.  It was the first DAC I have had that demonstrably improved the sound of my system so he would like to try it.  It would seem that the Ayre might have some additive benefit to his system, but of course he will only know if he tries it and it is evidently possible from a connectivity standpoint. 

It is not at all clear to me what the benefits of a "music server" or "music streamer"  are.   I have digitized my CD collection onto an 6TB external HD which I play through my iMac via Audivana connected by USB to my Ayre Codex.   I stream Tidal Hifi through my iMac to the Codex.  The digital set up cost me about $500 yet another pal just bought an NAD M50 for $3500 and I can't really see the benefit of it compared to my set up, given that he too has an iMac.  

Any thoughts? 

A new firmware and remote software was released yesterday by Sony.  If you don't do the latest firmware upgrade, Gracenotes will not work starting April 1st.
What happens with Gracenotes after April 1?  Will there be a replacement for Gracenotes?  If not what is the impact on using the HAP-Z1 ES?