If I just use a DAC, do I need a Pre-amp?

Many older dacs VC cut the bits at lower volumes

This topic has been discussed extensively. Many opinions on both sides basically concluding that the results will depend on the components in the system. Do a quick search...

It DAC does not have a built in volume control you need a preamp.HELLO!!

As long as you have volume control and you're happy with the sound you don't need a preamp unless you have plans to connect more components. 

It seems having a well executed volume control is one of the least appreciated and most important aspects of achieving high fidelity. Some of the top builders use massive multisection potentiometers withs shielding between the sections to achieve great sound. A preamp does far more than just "color" your sound w/r/t volume control - it preserves high fidelity.  In many cases you are leaving a lot of meat on the bone going straight from a streaming DAC (for instance) directly to an amp.