Isolation box please help

Yeah, I was just gonna suggest a pre-made iso-cab as well. Maybe they don't make for so much outside noise since they only have one speaker?
 
I thinked about it long time ago... Less compromise is to build a vocal booth like. Jason from audio hammer have something like this. Now for cost: between 1 and 2k euros.
 
On an editorial note, I'm always surprised at the number of guys here who don't seem to have access to band rehearsal space or any other place that they could use for full volume reamping for a couple of hours once they've got solid DI's.

this is definitely a good solution, you should look into that.

oh and OP, you asked a "long story short" question that was completely impossible and pointless so I gave you a long story short answer to your question, if you could "long story short" just make a box that sounds like a decent room then everyone would've done it ages ago don't you think? Not trying to flame the thread, I just felt the urge to answer your megaquestion with just the appropiate answer, and that's not even sarcasm. And have a beer and chill :kickass: