@celander Make sure you use RCA outputs if you are concerned about noise, Benchmark has pro-grade RCA - it runs at about 18Volts. This is a lot stronger than regular consumer RCA (2 volts) and confers a huge advantage. The SNR advantage is about 13dB.
Benchmark wrote an article about volume control in their older DAC 1. It is dated but the concepts are valid.
https://benchmarkmedia.com/blogs/application_notes/13095789-volume-control-technologies The Benchmark DAC 3 combines active analog gain control, passive low-impedance attenuators, a 32-bit digital gain control, and a servo-driven volume control. It basically uses a combination of Steve’s methods in order to minimize deliterious affects of excessive volume attenuation from one approach.
It is important to keep headroom so running signals as high as possible through an audio device and chain helps achieve the lowest noise. Running high signal levels is the way to do it and as Steve explained any attenuation through DSP, resistors or otherwise is going to reduce performance. A precision resistor pad on the output is an excellent way to allow a device to run at the highest signal levels possible and maintain good SNR while still attenuating the signal enough not to overload the next stage.
If you are really serious about noise then you should purchase their HPA-4 and run the Benchmark DAC with no attenuation at reference level (close to full volume) and feed the XLR analog output to the HPA-4 (for volume control prior to power amp). Personally I think this is overkill as the DAC 3 has one of the better volume control systems currently available on most DACs.
https://benchmarkmedia.com/blogs/application_notes/benchmarks-256-step-relay-controlled-attenuator 
