Oh, I'm looking for the truth alright! I wouldn't have spent the last 2 weeks optimizing this system just to prove someone wrong
Here's where I'm thinking the process will unfold. The Equipment Committee and I will set up the meeting room as per normal. I'll bring the extra equipment necessary to make this work as well as possible. I will have already optimized and level-matched everything, but then again, there is no harm in checking the record player set-up, verifying the level matching both electrically and spl, etc.
Most of the attendees are already familiar with the acoustics of the meeting place and the loudspeakers. It will only be the electronics and the sources (and dare I say the cables) that are new. I will start with a couple of benchmark pieces - music that the members have heard before so that they can assess if either analog or digital has been "dumbed down". If the members think that I have essentially made either analog or digital worse than the club's system, then the listening session is invalidated.
Then, going through the list of materials I have (and I expect others to bring), we will drop the stylus on either analog or analog-digital-analog input. We can either play the whole track through, or the members can ask for a switch to the other input (and I have the option NOT to switch to the other input). If members can not tell the difference, then of course I will not switch to the same input. If the members CAN tell the difference, then I might switch to the same input more often to see if they are still reporting a difference.
Listeners will have a clipboard with thinking/listening/talking points - and hopefully at the end of all this, we have a lively discussion about the experience.