Might as well use a dsp to that allows you to color the sound to your preference before it is sent to speakers.
By running analog into the ls50s, all you are doing is adding a conversion from analog to digital to the signal chain (assuming this source has a digital out). That digital signal is then sent to the same dac that the digital inputs on the Kef route to. All the kefs dac limitations are still in play. There is no native dsd benefit to be gained, no way to bypass the 192khz ceiling.
The best explanation for these various reports are pyschoacoustics, and that you are hearing what you want to hear. This can be an extremely powerful phenomena.
For those of you unwilling to accept that, then all that is left is that whatever sonic signature the analog source has, is being captured by the analog input, converted to digital, and then preserved all the way through the signal chain to the drivers. There is nothing “gained” here, nothing added other than the sources “color”.
These are very