DAC through a preamp or direct DAC to amplifier

It really depends on what you're looking for.

There are a number of digital network streamers that have built-in digital or analog volume control, and the results of using that directly connected to an amplifier can be better than if you insert a preamp into the chain.

But lacking a preamp you will not have as many options to support additional sources, if any. You may find volume control more annoying without a preamp and convenient remote control, or might want other features like balance or EQ or room/speaker correction that isn't found in your streamer of choice.

In addition, preamps can impart their own sonic signature which may be a plus or a minus.

My recommendation would be to first find the network streamer with the hardware and software that provides the quality and user experience you desire, and then decide whether or not adding a preamp will be beneficial.

FWIW we decided to go with Lumin streamers for the hardware, software, and sound.

As long as the DAC can set different output levels in the analog domain beside the digital volume control or has an analog volume control entirely, I'd go with a DAC direct route.

A dCS Bartok has 4 analog referrence settings for its outputs: 0.2V, 0.6V, 2V and 6V which would allow you to gain match your Pass amp and use the digital VC at the top of its range.

I ran my Mytek directly to the amps. It was a thin sheet of tissue paper better than going through a preamp.

In the end I switched to an integrated for a couple of reasons. Better amps, and nicer switching and volume control.