Yes you can put it straight into the amp, which is a great idea if your tt is your only source, or if you don't mind swapping interconnects from time to time.
If you are going to put it into the preamp first, you will want to set the volume control on the EAR all the way up. Of course, set your preamp volume very low and increase it until you find your preferred listening volume. You will want to adjust the phono stage volume downward a bit only if the the 68dB is putting the preamp volume control at preferred listening volume too low, so as to be on a non-linear portion of the volume control. (in such a position, it is more difficult to fine tune your desired listening volume.) The reason you want to put the phono stage as high as possible is that the volume control is really just an attenuator, meaning that the phono stage amplifies the signal by 68dB and then the volume control chops it back down. Since every event of amplification adds noise, and attenuation occurs more at the higher end of the dynamic range, the process of amplify/attenuate/amplify will unnecessarily decrease your signal to noise ratio.
Enjoy the music!
If you are going to put it into the preamp first, you will want to set the volume control on the EAR all the way up. Of course, set your preamp volume very low and increase it until you find your preferred listening volume. You will want to adjust the phono stage volume downward a bit only if the the 68dB is putting the preamp volume control at preferred listening volume too low, so as to be on a non-linear portion of the volume control. (in such a position, it is more difficult to fine tune your desired listening volume.) The reason you want to put the phono stage as high as possible is that the volume control is really just an attenuator, meaning that the phono stage amplifies the signal by 68dB and then the volume control chops it back down. Since every event of amplification adds noise, and attenuation occurs more at the higher end of the dynamic range, the process of amplify/attenuate/amplify will unnecessarily decrease your signal to noise ratio.
Enjoy the music!