Why are you looking at a rig like this to jam at someones' house?
Even if you buy the Boss box (they're OK), you have no power amp to drive the cabinet!! And no need for the ALTO, which is pretty cheap gear in the first place. Not to mention that the cabinet is insanely overkill-it's designed for a loud stage rig!
Instead of getting the compressor (the Boss has that function built into it, and it's probably more suited to the guitar, anyway) and that big cabinet that STILL needs an amp to drive it (!), look at something like the Tech 21 Power Engine 60. There are a couple of models available, and they are designed with YOU in mind! They are able to take the low line level signal from the Boss box ( or any other modeller/preamp unit), and amplify it with QUALITY SOUND and it's built like a truck! Not to mention that it's a heck of a lot more portable than that VW-sized cabinet. Tech 21 makes some serious, professional gear for the player, check out their website.

Okay thanks for the reply.

So if I'm correct I can plug the BOSS GT PRO into the Tech 21 Power Engine and I'm ready for lift off?

Exactly! And if you can swing TWO of the Power engines, you'll have stereo!!! Enjoy!

Thanks alot moonbaby!. I'll get two.

Hey moonbaby, I looked into the amp and its a beaut.
When I wanted to order them I found out that because I live in the 3rd world upside down country of South Africa.

I was told I can get the 2x12 PE 60 for $449

now the exchange rate from USD to ZAR South African rands is R7 to 1 USD

ie : $449 = R3200

new problem

because there is a distributer here in ZA they havent got the amps into the country yet because of high freight costs on heavy weight items.

I was told that I should budget for R7800 for bringing ONE PE 60 into my country.

that means if its gonna be roughly around R7800 for this amp then the freight cost is going to exceed the product itself.

This is unacceptable and has left me with a new question.

You seem to have carnal knowledge on the topic of sound so is there any other more generalized/well known AMP make that does the same thing as the Tech 21 PE 60 that you think I could look at and that stands a better chance of being in my country?

like marshalls and so forth the big names are hear.

but one that will still bring out the BOSS GT PRO without having an amp infringe or falsify the rack because of its own settings.

something exactly/similar to the PE 60 in ability that should be available to me without importing?

Please help

R7800 / by 7USD = $1114 for one amp... ouch.

Also USA works with different voltage than ZA and I was told that if something goes wrong the distributor told me I got no backup as no one will be able to service my imported gear which is not a good thing....