The "preamp" function is somewhat of a confusing issue, as many folks consider "preamp" to mean that the DAC can be connected directly to an amp and can use its own (remote if possible) volume control. Well, this is true of ALL Mytek Stereo 192 models, not just the one they call "preamp" (to differentiate it from the "mastering" model). The way Mytek defines "preamp" is to add rca analog inputs into the DAC, thereby making it not only a volume attenuator but also both a digital (of course) and analog switcher.
As a remote volume DAC (the remote codes are in the user manual and work perfectly) it is ok, but not great. As Michal and I have discussed ad nauseum, for a budget of $1500 they had to make sacrifices, and one area IMHO, is the variable analog stage. It suffices, but is wayyy better (again IMHO ) in bypass mode, which then requires the user to use a preamp or integrated amp (or active speakers, etc). Also, as a Mytek-defined preamp the analog ins are clean and would suffice for someone who primarily listens to digital but needs a secondary analog source for those few times.
Note: the simple difference between the preamp model I am discussing and the mastering model Bruce is using is the choice between RCA analog ins or a set of pro-level SDIF DSD ins (Bruce can hook his Sonoma directly to it). In both cases, remote analog volume is still a menu selection.
As you can tell, this little wonder box has a lot of features, not to mention user set-able DSD and PCM filters, upsampling, etc.
This is a quick review as I found as well the dac is best used in biomass with any volume control. And it greatly improves how it sounds