My DAC (AK4384VT) specifies 3.4Vpp output voltage. does it mean relative to 0V such that there is -1.7V to +1.7V excursion of the signal or does it mean relative to +1.7V such that the signal lies between 0 to 3.4V?
Read Note 6 of datasheet:6. Full-scale voltage (0dB). Output voltage scales with the voltage of VREF, AOUT (typ.@0dB) = 3.4Vpp × VDD/5. If you supply 5V, you will get 3.4Vpp swing.
The analog output will swing at half of 5V, which is 2.5V. The peak voltage will then be 2.5V + 1.7V = 4.2V and 2.5V - 1.7V = 0.8V. The signal will always remain in positive DC region, it won't goes negative unless is a different kind of DAC that uses dual supply.
When you are connecting the DAC into another opamp circuit with a reference voltage of 6V. It is a must to add a DC blocking capacitor between them, with the + of the cap facing the higher DC voltage.