Preamp for R2R DACs

This is exclusively for my office setup. Currently I have a dedicated HP laptop with high spec as my core for Roon playing out of OPPO 105 USB dac running KRK rockit powered speakers. Been interested in R2R dac like schiit Gungnir or yaggy - the only problem is these DACs do not have a preamp like OPPO does. What options do I have to run my music volume control for such a setup. Keeping in mind this is for my office and I don’t want a big preamp/amp unit since I have powered speakers. 
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Just get the smallest Schitt preamp, it costs around $400, and it will provide the volume control you need.
Thanks for the reply. That makes sense - it’s only that I am afraid of potentially introducing a weak link - preamp in this case - as I am sure it’s opening a can of worms as to which preamp is better etc.