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

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