Aurender W20 is an excellent source and it's sound quality completely depends on the DAC quality. But if your DAC has internal clock and has no clock input, then there is no sense in using W20, S10 will sound equal to W20 in this case.
Linn Klimax DS is the best digital streamer I have heard so far. I think the situation will change as soon as MSB release their Network Renderer which will turn their DAC IV plus into digital streamer. It would be very interesting to compare Klimax DS with fully loaded Platinum DAC IV plus.
By the way, Lumin use the same "cheap" and "old" parts in all their models as well, because their streamers in general are copies of Linn's. But Linn streamers have high quality firmware, which Lumin streamers lack of.
Yes, it is logical to compare Klimax DS with Lumin S1. But the difference between Klimax DS and and Lumin A1 is more significant than between Klimax and Akurate DS, so S1 should sound much much better than A1 to compete with Klimax.