I've no idea what the differences are but I do know that on one PC I use VAC and on the other VB Cable. Always used VAC in the past but it won't play ball on this particular PC.For my setup I use VB Cable with any RTL dongle with SDR Sharp and PDW 3.1 and it works perfect. I don't know if it has anything to do with the difference between VAC and VB Cable but it works great.
I've recently come into the possession of two Pi2B's that I would love to explore a setup like what you describe. What RTL-SDR "server" are you running on your Pi3 that will feed a datastream to SDR#? Best I can tell, the largest difference between Pi2B and Pi3 is faster CPU in the Pi3. While a definite plus, do you think a Pi2B will suffice? I would like to setup two of them to potentially feed a trunking setup, or just dual "VFO" if nothing else. I assume you have gigabit backbone. Any issues with packet loss or latency that negatively impacts SDR# decoding of the TCP stream?PDW has routinely been problematic for me, using VAC's to pipe the audio never gave me a strong enough data stream.
the meter rarely rose above half and was constantly getting the yellow alert triangle.
Solved all this by completely altering my set up..
No more RTLSDR connected to the PC.
Raspberry Pi3 does all the CPU work..over home network, via ethernet.
.SDR# is running in TCP client.on a 2G ram/1.6ghz cpu DELL Inspiron 1501
Now using a simple stereo patch cable to pipe the audio to my Dell XFR and now DSD+(with LRRP working Great) , KGAcars and PDW perform ridiculously well..even while running RTL1090 & ADSBScope and Trunk88..
Now i have too much going on...Too much data being displayed...(ha...first world problems, Eh!?)
Absolutely possible my VAC's are not set up propper, but after years of struggle, its choochin along great..
And at this point..It aint broke anymore..so..........