What do you take when demoing new gear?

For me, what I would bring depends on a lot of factors, including your relationship with that dealer.  First of all, I would burn a CD with about 10 different songs, so I don't have to keep getting up to change a CD. If I wanted to buy a new CD player, I would bring my old one to compare, but I would ask in advance of course.  Any good dealer should be glad to do an A/B for you.  When I was purchasing an expensive amplifier, I brought my Harbeths in, as they were not a Harbeth dealer.  But I was spending big bucks. But I would not walk into a dealer cold with a set of speakers without asking. it would be easier to answer your question if you told us exactly what you intended to buy, what you had and what your relationship with the dealer was.  

A pee break followed by a large cup of great coffee ;-)

Been there, done that. One of the reasons I became so insufferably good at this, I put in the work early on. Took my then ten years old Magnavox CDB650 to compare with Proceed. Took my patch cords to compare with XLO interconnects. Even hauled my Dynaco ST400 into a shop one time!

This was all while going through that awkward stage where you have a hard time hearing things, or you hear them but aren’t sure what you’re hearing, so your head is so full of doubt you don’t know one end from the other. Its real easy at this stage of the game to fall prey to things like dragging along your "reference" recordings.

Looking back on it, I would probably still bring along something like a power cord or interconnect, something easy to carry around, plug in and compare. But that’s about it.

What I would do instead, the one thing of more value than any other, is make the dealer change something. Ask to hear another power cord. Interconnect. Whatever. Anything. Just make him change it, so you hear the same system only with one thing- and only one thing- different. If they have cones or elevators or whatever ask to demo them. If you have your own cones or springs that’s a great thing to demo, especially if you can fit them in your pocket.

Most important of all, bear in mind that whatever you do- and whatever they will allow you to do!- varies tremendously from place to place. Some places like here in the Seattle area they’re so spoiled with IT people utterly clueless yet flush with cash they don’t want to spend one minute of their precious time on anyone its not immediately apparent they can snow in to dropping 50 large on AT and D’Agostino in the next 90 seconds. Find the right place though, one with the time and the patience to indulge your ineptitude, you can learn a lot. So its worth the effort. If you are smart and buy something then he sees its worth his time and so much the better for the both of you.

I gotta say this, don't get mad. We use to DEMO buildings.. LOL
Destroy them.. words count.. I mean DEMO.  Then build a new one!!
There was a lot of sound involved for about 1 minute.. Yup..

Not even one song worth.. Demo!

OP, I asked some stores to do some weird stuff, most will actually do it..
I drug in a speaker (center), a stool, I use for proper height, (it goes everywhere), GOOD camera,  tape measure and  my SPL mic is on my phone.. The stool doubles for a Mic stand  I feel like Jerry Lewis in  "The nutty professor".  It gets me some serious looks, but it works.. I have a test CD, tones and music. The chair back at one meter is a constant for measurements and an 8 x 8 x 8 or 10 x 10 x 10 triangle.. for some testing.. and the chair back..

I found a LOT of the sensitivity data way over stated. 

No more than a tote bag and a tripod folding chair, with a back and pockets. Less the speaker, that was a one off..

OP it's your money, just ask...BIG grins help too

Regards