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

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. 

davidgwillett OP

The old saying "best preamp in the world" "sound like a piece of wire".
Guess what that’s what going direct is, and then passive and last an active preamp.

And if you don’t like direct and your not "bit striping", then you don’t like the sound of your source, change it, don’t add another expensive problem into the mix.
As Ivor Tifenbrun (Linn LP12) said, it all starts with the source, get that right and your almost home.

Cheers George

John Atkinson's review of the Pass XP-30 preamp is a pretty interesting read relative to the question of to use a preamp or not; e.g. https://www.stereophile.com/content/pass-laboratories-xp-30-line-preamplifier

He starts by referencing the Ayre KX-R preamp with

So much for the effect of expectations on perception: the KX-R sounded better than no preamp at all! As Wes Phillips described in his review, music sounded especially alive through the KX-R, whereas with the Transporter driving the amplifiers directly, it was all a touch less involving; acoustic objects within the soundstage were all a tad less fleshed out.

But it could be argued that my finding should not have surprised me. Ever since reviewing Audio Research's groundbreaking SP-10 preamplifier in July 1984, I have suspected that the preamplifier is the heart of a system, that it colors and adds its own character to every signal that passes through it. What I hadn't anticipated was that this character might not be a mere absence of negatives, but could also be a positive attribute.

and concludes with

The XP-30 has rekindled for me the concept that the beating heart of an audio system is the preamplifier.