As others have said, a screenless desktop would be best, but a laptop will certainly work.
If your DAC connects through USB, try to connect the external hard drive with something other than USB. USB works in series, so real time transfer of music to the DAC and data exchange with the hard drive will go though the same pipe. Avoid if you can.
As far as software, I found a very significant improvement by using Windows Server 2012 in core mode and using AudioPhil's Audio Optimizer (which only works in WS2012). Very, very significant.
Other than that, the cheapest laptop will do. You don't need much processing power or RAM for this, and you should shut down all hardware bells and whistles to minimize electrical noise as Kinjanki mentioned, so why pay for that? You need minimal processing power.
If going WS2012, however, it needs to be a 64-bit machine (any new machine will be, but you could even get a used one).
I think optimizing hrdware on a laptop is a bit of a waste of time. This, coming from a guy with a heavily optimized headless server.
If your DAC connects through USB, try to connect the external hard drive with something other than USB. USB works in series, so real time transfer of music to the DAC and data exchange with the hard drive will go though the same pipe. Avoid if you can.
As far as software, I found a very significant improvement by using Windows Server 2012 in core mode and using AudioPhil's Audio Optimizer (which only works in WS2012). Very, very significant.
Other than that, the cheapest laptop will do. You don't need much processing power or RAM for this, and you should shut down all hardware bells and whistles to minimize electrical noise as Kinjanki mentioned, so why pay for that? You need minimal processing power.
If going WS2012, however, it needs to be a 64-bit machine (any new machine will be, but you could even get a used one).
I think optimizing hrdware on a laptop is a bit of a waste of time. This, coming from a guy with a heavily optimized headless server.