Yup. You want at least 3 dBs of headroom, that is to say that on average the signal is peaking at around -3 to -5 dBs.

When you're finnished recording your mix go to what looks to be the loudest part in the mix and select about 5 seconds of audio data. Now go to Effects->Wave Hammer. Tick the "Bypass Compressor" box. Next go to the tab labeled "Volume Maximizer" (which is at the BOTOM of the plugin - wierd huh!). Tick the "Use longer look-ahead" box. Right click the right most meter and select "-12 to 0 dB". This meter tells you how much the limiter is chopping out of your signal. Now click "Preview". On the default settings it shouldn't even register unless you've got a big spike caused by a pop or scratch on your vinyl. OK, now start playing with the "Theshold" slider. Bring it down so that it juuuuust makes the right hand meter go red every second or two (you can adjust it in .1dB increments using your mouse wheel and holding down Alt). Now click "Save As" and save as a preset. Select your entire mix, load up Wave Hammer, select your preset and Click OK.

Your mix will now be at the loudest possible level without having the tracks being compressed.

Happy mixing!