A question to roon: would you please implement a function to allow user to choose a number of cores for dsd upsampling. So not only to switch parallelized processing but also to choose the cores number would be very helpful. Thanks!
Sounds like an excuse to me, to avoid the complexities of parallel computing. There are many C++ compilers supporting OpenMP extensions, and there are also STL execution policies, to name just a couple of parallelization techniques.
Well, filtering via FIR convolution and IIR parametric equalization also is a serial operation if performed natively in the time domain, which I believe is how Roon DSP applies such processing. Per my understanding, Roon DSP does not convert to the frequency domain by applying FFT and inverse FFT to the audio and filters.
Roon implemented already a parallelization with 2 cores. And it looks not as it is one core per channel. So it should be possible to do further parallelization. Nuc10i7 has 12 threads. It is enough potential to spend some more threads for dsd processing.