Taking your system to the showroom: drive em crazy

The problem with dealer's showrooms is that it can't work for me when I want to test a particular tweak (cable, preamp, CD player, etc.) against my system. Don't you think you should be able to load it all up and drive it down to his showroom and allow you to see what his so-called ultimate cable, etc. can really do for you in his otherwise controlled environment? People keep talking about how one's answer is okay, but that it might not work in other situations, given the variables of other systems. Of course, hauling a 250+ pound Amp or pair of speakers into a showroom is silly, then again, is it?????
Yes, it is. Especially since you can't haul your room to the dealer's. Arrange to take home the 'tweak' (a CD player is a tweak?) instead, either on a loan, deposit, or refundable purchase trial basis.