I listen to music that the client has, but if they listen to mainly MP3, I explain that if it sounds amazing with those, anything of higher resolution won't. I listen to human speaking voice- if it sounds natural, that's a very good starting point because I have heard a lot of well-known speakers that are highly regarded do a terrible job with speech.

We can't know what the other person hears- everyone's hearing is different and they can't usually convey this in words, but we can ask probing questions to get an idea.

If I'm evaluating speakers, I listen to music that sounds good on my systems, which I know well and that was recorded well. I want the instruments to sound real- I know that recordings are an illusion, but if I know what instruments & amps were used on a recording, I want to be able to identify them by their sound.

Speakers that cause hearing fatigue are eliminated as soon as it happens, but if it's only one recording that does this, I listen to more music (and go back to the one(s) that sounded bad) with fresh ears ASAP to find out if it was the speakers or the music. I have a few recordings (all on CD) that I don't listen to because they're very harsh sounding.

The live Return To Forever recordings from 2008 and 2011 were well recorded, but the low end is a bit hot, so it's a good idea to ease into it to avoid speaker damage.