Digital Preamp with USB-input but without a DAC?

I have been looking for preamp with USB input, but without a built in DAC. I cannot find any. Maybe there is a good reason for it, but is my requirement, so special? 

I have an Innuos Pulse mini streamer connected to a pair of active Buchardt speakers though Platin Hub. Right now the streamer is connected with RCA to the Hub and Wisa to the speakers. However, there is a DAC in both the streamer and the speakers, so I do not need an additional DAC. Hence, I am contemplating running USB from streamer to Hub to allow for the digital signal to be sent to the DAC in the speakers. However, it turns out that the Platin Hub cannot do volume control via USB, which I why I would need a preamp. 

Any advice?