Hi Mark and welcome to the community.
I think that first and biggest item arising from your post is what is DoP?
You seem to be under a misapprehension that that DoP is something different from DSD and that the DSD data is turned into something else. DoP is DSD - it is the same data. The only difference is it is packed in a way so that it can be transmitted via an interface more commonly used for other forms of data e.g PCM. Please see this FAQ:
DSD pass through is really meant for when a sequence of mixed format tracks are received by Upsampler e.g. 44.1, 48,DSD,44.1. If the upsampler output is set to say 176.4 then the output with pass through set would be 176.4, 176.4,DSD, 176.4.
However Upsampler is only able to accept DSD input as DoP format on any input aside from Network which will accept the usual DSD .dsf and .dff formats. Unfortunately your Aurender does not have a network output.
In regard to your question:
If you only play SACDs from a dCS transport then the Upsampler is not required. However if you were to play DSD files from NAS then you would, of course, need to use the network player facilities of the Upsampler and this would involved DoP except with network connection.
However, in any case, the best interface with current dCS products is not USB ( irrespective of the data format it carries ) but network connection. Unfortunately the Aurender does not, I believe, have provision for this.