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

One DAC, has an analog potentiometer, the other from the software player.

These are the specs of the DAC I plan to use.  https://www.fiio.com/m15

As posted above - tried and liked already.  I may try a pre-amp in a month to see if I like the sound color.  Mainly because as a vintage one, I expect I can sell it for what I paid and then some.  I would not buy a new pre-amp even if "better" as I'm more likely to not get my money out of it.

Subject = Ad Nauseam........My Luminous Audio Axiom, Walker mod, 3 in, 2 out, with remote, is just what the doctor ordered. I do not hear it, in my signal chain. The chassis does not resonate, the connectors and wires are top notch, the switch and control, are also, top notch. It works with my 3 dacs, 4 tuners, and my many ( still ) amplifiers, and is, ime, and imo, perfect....for me, and, that, is all that matters. Enjoy, and stay safe.....Always, MrD.

If you have the availability of software attenuation, i.e. ROONs media playback software offers the option, then you will want to compare use of the software volume control versus the hardware volume control. 

Results will vary on performance, and there is no telling prior which will be superior. I always compare the two regardless of which integrated DAC is being used. Results are not universal; with one integrated DAC the software vol. control yields a superior result, while a different integrated DAC I use yields an opposite result, and is far better with the hardware vol. control and the software output fixed. You simply must try them both. 

Beware that if you are not careful, a software volume control can be bumped, touched and send the system into max output. Caution is necessary when using such attenuation. However, dedicated DAC direct to amp is always cleaner, if not fuller. YMMV 

I strongly recommend the addition of SONORE's systemOptique to convert Etherent signal to optical, as it drops the noise carried on Ethernet. Striking change, improvement. See my article about it at Dagogo.com  

I have no interest in arguing with people about "bits" and resolution, etc. Superior performance is easy to hear. 

" I strongly recommend the addition of SONORE's systemOptique to convert Etherent signal to optical, as it drops the noise carried on Ethernet. Striking change, improvement. See my article about it at Dagogo.com"
From Dagogo article:
"For Dagogo readers still spinning discs or streaming audio through a Mac Mini or similar, this article is for you. "

Which really isn't me.  The primary DAC referenced above is really a DAP.  I am not streaming for this application, rather play downloaded files.  I may look at this for the Qutest where I do sometimes stream.  

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

the Atma-Sphere MP-1 or MP-3 will serve you well for years to come without regrets.