Hi, forsooth,
Not intending to confuse things but here’s another option you may want to consider...
I was doing something similar to your situation with my laptop and desktop/main stereo systems and got tired of changing connections each time so I bought a Bluesound Node 2. It has a built-in DAC with RCA output to a preamp but you can also use the S/PDIF digital output to an external DAC such as in your P5 preamp. It’s a decent music player in its own right so you may not even need the DAC on the P5.
The Node 2 can be connected to your internet router with an ethernet cable or wi-fi and streams music from the web or from a music library stored on a USB drive connected directly to the Node 2. It also streams from a NAS drive connected to your router, which is what I use now. The Node 2 is controlled using BluOS software on your laptop. (More info at bluesound.com)
The Node 2 is discounted right now for $450 USD directly or through MusicDirect.com. My hunch is that Bluesound is coming out with a revamped line up of players/speakers so they’re getting rid of stock.
So with a Node 2 you can have it sitting discreetly with your main stereo system and stream internet stations as well as ripped or downloaded music stored on an external hard drive, all controlled by your laptop, tablet, or smart phone from wherever you want.
Just an idea. =)
Regards,
Tom
PS: There are less expensive alternatives to the Node 2, such as the Pi players available from allo.com but the Node 2 is really easy to set up and start playing music and not that much more money.