How to set up volume control on a DAC without a preamp

I have used the ps audio dac with Ethernet for years and had Roon use the dac as an endpoint which I controlled the volume thru Roon. 
Since I wanted to use i2s, I am using the airlens in front of the dac and Roon connects to the airlens as an endpoint.

Since I got rid of all my vinyl and analog pieces when I was using dsd and MQA, I also got rid of my McIntosh preamp, after I tested the sq with and without the preamp, and my system sounded better without the preamp.

I have 2 Benchmark LA-4 pre amps. Love them.  Rory at Benchmark is great to deal with. Reasonable price, 30 day trial period, Made in New York. Adjustable bias, etc. Robert TN   Bet you keep it!!

I also have the Benchmark LA4. I find a volume control on a DAC not a feature but a bug. The LA4 is for people who do not want the pre to color the sound.

Using a preamp like the LA4 (or the almost the same Holo Serene) will take your DAC to sonic levels that a built-in volume control never did for me. I use my 2 preamps on costlier amps.

The Topping pre90 premp is much cheaper and measures like the LA4 (and Serene) but it had many negative issues for me.

I would also be concerned driving an amp directly from a DAC. 

This was a big issue for me when I used the Musetec 005's DACs volume control. Those little buttons also make it hard to quickly lower the volume.

As others have said, the Schiit SYS is probably the simplest way to get a high quality potentiometer into your signal path. They make good stuff. https://www.schiit.com/products/sys

Carlsbad an endpoint is a usb or etherner device so of course it will work