don't know if one or two would be enough.
Demo'ing/auditioning components is a very tedious and complicated process, but it can also be lots of fun. When going to stores, you are also auditioning the salesperson and the store, so things like their selection, listening rooms, and helpfulness are also important considerations.
When you go is also important. If you are going to audition a number of components in one visit, it will require a lot of time, so it's best to visit the store during a less busy period. It's a good idea to call the store in advance, let them know what you are trying to accomplish, and determine when it would be the best time to come. For auditioning a single component like speakers, I think you would need at least an hour. Amplifiers require more time, and for wire/cables, more still.
This just allows you to narrow the field. You can't really make a final decison until you've taken it home for an in-home audition.
As far as music is concerned, this will be dictated a lot by personal tastes, but even so, I believe you need to listen with a wide variety of acoustic instruments recorded with as little miking and mixing as possible. I like to start with recordings of small ensembles that have a nice spread of performers accross the stage. Chamber music, jazz quartets, and bluegrass have lots of good examples. I then like to listen to male and female vocalists as soloists and as groups. I listen for things like image specificity, separation, coherency, and natural timbre of instruments and voices. This eliminates lots of contenders very quickly.
If I like what I'm hearing, I will move on to more complex and demanding music to test the frequency extremes and for signs of congestion. I will also play selections that I may not necessarily like, or music that might sound particularly bad on my system to see how it compares when played on the component I'm audtioning.
I seldom play an entire selection; it may only be a few seconds of a track that I'm very familiar with just to compare how this very familiar passage sounds on the auditioned component.
And I never try to evaluate more than one component at a time like speakers and amps, or amps and preamps, or cd players and digital cable.
that's my cents
