trying to upgrade speakers

A home demo is absolutely the best way to go. Other ways to demo are to go see them at a dealer (per SoGood's comments) or attend an audio show (Rocky Mountain Audio Fest upcomming in Denver), or buy used, see if they perform to your standard, then keep or re-sell depending on the outcome. It is the best way to have peace of mind that you have made the right choice and that your conscience is clear. I echo Elsneb's comments regarding the GMA Callisto, you have to start somewhere with a speaker choice to home trial. I would be surprised if you couldn't work out a deal with a GMA dealer to try before you buy. Home demos are how I have stayed with GMA speakers for the last 1.5 years vs. four others in the previous 2 years. Check them out.

If a dealer will not let you demo at home... find a new dealer. There is too much competition on the internet not to. But do try to stick to your local dealers if they prove to be honest and helpful. It is a little dirty to test a dealer with loaded questions but it is a quick way to see if they are going to be straight with you.

Ask your local dealer if you need a $400 pair of interconnects with your new Sony receiver and Infinity speakers. If he laughs or nicely explains the futility of doing so you have a straight shooter. If he says anything verging on "yes" then be warry if not outright affraid of his corrupt business practices.

Similar questions for improving the same set-up would be for better (Monster) speaker cables, better terminations on said speaker cables, new (Denon because its the best that Crutchfield has to offer) DVD player, or sorbothane feet for your receiver. THe answer to all of these questions should be "no."

Good luck and have fun with the new hobby!

will the green mountain callistas give me a bigger sound than the mobile fidelitys that i have?
the size of the tweeter and woofers are pretty similar

Green Mountain Callisto really took my breat....that is a truely amazing speaker, I also wn Electrostats, so I have to agree with Doug, but I can tell you it would be next to impossible to imagine you not loving the Callisto....truely world class sound.

i live in the new york city area and there is
no way i know of short of actually ordering apair of
ither tyler acoustic linbrooks or the green mountain
callistos. most dealers ive been to are pushing
speakers that they sell (obviously), which is why
ive only heard b and w triangle spendor and a few others.