Hi all,
So I had a more experienced friend around the other night for some testing of equipment (Bel Canto Dac vs the Bryston). It was a fantastic night.
I learned a lot as I could not spot the differences between the dacs at the start of the night but I could by the end.
My question is whether there are books articles or general techniques in critical listening that have been written before?

Robert Harley's The Complete Guide To High End Audio has a section on Becoming a Better Listener

Tip 1, don't talk whilst music is playing. Tip 2, resist the urge to make a rapid summary judgement. Tip 3, refer to Tip 1. It takes time and not all differences that you might hear are for the better.