I mean that I dont know if its a good idea to go from your turntable to a preamp and then to the nuforce HDP. a DAC is a Digital to Analog Converter. Turntables convert the back and forth motion of a needle in the grooves of the record into electrical signals. Those electrical signals need to be amplified, which is why you'd need the pre-amp. Note, you only need a pre amp if your turn table doesnt have one built in.
At this point you already have an analog audio source so why would you send it to a digital to analog converter? You would need to figure out how the analog input jacks work on the Nuforce. If the analog input jack does a complete bypass of everything and outputs the same thing, you're fine connecting it there. If the Nuforce takes analog data and converts it to digital, then back to analog before it reaches the headphones, your efforts are completely wasted as that will only ruin your audio quality. If the HDP has its own preamp built in you dont need a preamp.
Like I said, you need to use google and figure out your product specs and everything yourself. half of this junk is in the manual but somehow i doubt you noticed the HDP came with one. look what happens when i go to www.google.com (incase you didnt know what google was) and type , without quotes, 'nuforce hdp turntable':
http://totallywired.co.nz/nuforce_icon_hdp.html
That page pops up. then i press ctrl+F to open the search box and type in 'turntable'. within milliseconds, i see this line:
I want get more performance from my CD or DVD Player.
I'd like to even listen to my turntable.
so i press 'enter' again to find the next instance of the word 'turntable' and OMG look what just happened!:
The fact that the HDP is also a quality active preamplifier delivers even more advantages. While most DACs are fixed level, the preamp section in the Icon HDP means we are able to connect to far more components and systems. Because this section is analogue, it allows us to connect any line level input - a conventional iPod dock, radio tuner or even turntable (via a phono stage such as the Cambridge 640P or Dynavector P75Mk2). The HDP may be small but the output is more than ample in power - you can drive any power amplifier, active speakers or conventional system with it.
Incase you arent sure how to read and research yourself, that basically says that you dont need a pre-amp if you have the HDP. if you connect anything to the analog port, the HDP will pre-amp for you. You take your turn table's left/right output and put it into the left/right input on the HDP. then you turn that knob to A for Analog and turn on your turn table.
You do know that turntables play large vinyl records and not off-the-shelf shiny CD's, right? and that vinyl is extremely sensitive so you need to care for it and dust it, then lubricate it before playing unless you want it to degrade horribly every time you play it? and that you need to know what speed to play it at and how to use the turn table to set the speed, which in turn requires that you read the manual rather than just plug random crap in and see if it works? Its high quality audio equipment, not an ikea bookshelf. dont experiment to see if it works, just do it right the first time.