Well as surprising as it may seem, the Naim product development engineering teams did, and may still have, a method of optimising software instruction execution timing such that they can fairly reliably act as a crude tone control with the perceived analogue output. This involved things like carefully timing when to read and write back to memory, load registers etc. By doing this one was changing the noise profile of the voltage lines, ground plane and electromagnetic fields caused by the digital electronics… and as we know changing noise profiles, or what is often termed noise shaping, often alters our perception of the audio ‘quality’