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

I recently asked a Facebook group this same question.  I should have asked audio forum folks first.  Sorry if there is overlap.

If I only use DACs for my amp, why do I need a Pre-amp?
I have the opportunity to get a nice Fisher 400CX-2...but why?

I have volume control on my Fiio M15, and volume via my player for my Chord Qutest.  How will a pre-amp make things better.  

@phantom_av " Pre-amp is the heart of your Audio System every device is connected it to except the Speaker."

For me "every device" is one device. 
For this thread it is a DAP (no stream) 256 and 512 DSD player on the device to the Amp or DAP->pre->Amp.  
-I have an analog volume 
-I have filters (EQ)

I will wait for my free test.  If someone offers a money back test, I may test, but I expect they will get their device back. 
I'm a bit more confident now than in the OP as I had not tested then.  Now having hooked it up to some guys amps that insisted I need a pre-amp and now they don't.  He said come back in a month and try.

My setup/s are very simple.  They are also in different places.  It may be wrong, but I have a source/amp/speaker setup. 

I switch setups, not components.  So far, there are no pre-amps.

The source determines the DAC and amp and speakers.  
(this OP) Fiio M15 player local data ->Fisher SA-100->Klipsh Heresy

Then other stuff:
Windows 10 Audiovana Player ASIO driver to Chord Qutest -> 300B SET -> Chartwell

As above to HH Scott -> Watkins Gen 4

Same DAP-> http://www.erhard-audio.com/Elvis.html ->Maggies
(another state)

The only time I might switch source on the same amp is on the Scott for a TT.  I have about 8 records.  Everything else the source is matched to the amp and the amp to the speakers.  

And JA concludes with

The XP-30 has rekindled for me the concept that the beating heart of an audio system is the preamplifier.
Yes Nelson Pass is in business to make money, even from his preamps, if people want them.

Yet Nelson Pass also quotes this:

Nelson Pass,

“We’ve got lots of gain in our electronics. More gain than some of us need or want. At least 10 db more.

Think of it this way: If you are running your volume control down around 9 o’clock, you are actually throwing away signal level so that a subsequent gain stage can make it back up.

Routinely DIYers opt to make themselves a “passive preamp” - just an input selector and a volume control.

What could be better? Hardly any noise or distortion added by these simple passive parts. No feedback, no worrying about what type of capacitors – just musical perfection.

And yet there are guys out there who don’t care for the result. “It sucks the life out of the music”, is a commonly heard refrain (really - I’m being serious here!). Maybe they are reacting psychologically to the need to turn the volume control up compared to an active preamp.”

Cheers George
A DAC with a volume control built in may be just fine, but then again, it may sound better running through a preamp. It depends on the "match" with the power amp you are using. I run a BelCanto DAC/Pre straight into a pair of Bel Canto mono amps with excellent sound, but they are designed to work together without the need for a preamp. Try before you buy if  you can.
to my ears, preamps impact the system's tone, speed, and resolution. to me and in my system, they have had more dramatic impact than amps (that's not to say that amps and other changes haven't). i picked up a nice soulution pre and am never looking back. i've done the dac with volume control but it's not for me.
Yes you can, but the impedances of the equipment might not match, causing anomalies.