Dumb question......why do you need a preamp?

You will always have a preamp, inside integrated amp, or separate preamp+poweramp. 

You can't just take 2V output of your DAC (or phono preamp) and go directly into the power amp. You would want to have volume control and input switch, otherwise it would play at 100% volume. Simple passive attenuator is simplest preamp (maybe not the best sounding, but thats different story...)

This question isn’t’ dumb at all. Digital components have a high output analogue section that -very rare extreme impedance mismatches excluded- only need an attenuator to drive the power amp. Preamps were designed for the opposite purpose: bringing up low or very low output from phonostages to where an attenuator could even be used. In other words: they are a bit of an anachronism.

Most AVR’s and Integrated Amps just have way too much under the hood driven usually by an insufficient power supply. Myself I found I’ve been able to achieve the most satisfying sound to my ears utilizing a dedicated unit with each having it’s own power supply at each stage of my set up.  After years of the AVR / Integrated Game I’ve come to the conclusion performance is sacrificed when you settle for versatility.    

If you have a DAC like Audio Analogue's that has an analog volume control, you don't need a preamp. 

I have a vinyl rig and send the signal from my phono preamp to my DAC and out to my amps. No preamp.

Preamps are merely expensive volume controls. 

A lot of good advice.  If you have an integrated amp and it has all the inputs you need and it controls your system the way you want it to you should be set.  If you prefer separate components with a stand alone power amplifier, you will need a separate preamplifier to connect to your power amp.