Since, apparently, no one has done a direct comparison of the Cal Sigma with the Benchmark DAC 1 or the PS Audio, FWIW, maybe this is as close as you can get: I had a dac of approx. the same era, the MSB Half Nelson with upgraded power supply, and the Benchmark DAC1 ate it for lunch.
My friend had a Cal CD player of the same era, then replaced it with a new Classe CD 10 (I think it was), which cost $2,000 and was much superior to the Cal CD player, he thought. Then, he sold the Classe when he heard my Benchmark DAC1, which he felt was better than the Classe, and got a Benchmark also.
Looking at your system, I think a DAC1 would work very nicely, but be sure to use a reasonably good transport and a good digital cable.
Hope this helps.
My friend had a Cal CD player of the same era, then replaced it with a new Classe CD 10 (I think it was), which cost $2,000 and was much superior to the Cal CD player, he thought. Then, he sold the Classe when he heard my Benchmark DAC1, which he felt was better than the Classe, and got a Benchmark also.
Looking at your system, I think a DAC1 would work very nicely, but be sure to use a reasonably good transport and a good digital cable.
Hope this helps.