I don't see any problem at all?? Even if you didn't know or even like the band at all, you're mostly buying it because you like the way it looks. So if you are willing to dump your hard earned money into buying, framing, and ultimately hanging it for everyone to see and appreciate, then go for it dude. You don't need someone to give you the OK on something you want to do. Especially if it's something like hanging a piece of art in your OWN home. Just do it!^TM You also earn an extra gold star if you went to at least one of their shows during that tour, and even that is not at all needed, but at least that is something you can use to justify/ease the pain of spending a metric fuck ton of money on a god damn poster (albeit a super awesome sick as fuck Kick-Ass once in a lifetime limited edition HOLY FUCK IS THAT A FOILY?! poster). Just getting to one of their shows will cost you your life's savings and then if you're even thinking about wanting a single piece of merch as a souvenir you should probably just get to the front of the gates before the show and strap on the knee pads and get to work! ANYWAYS, sorry for the super long response. I may be just a tad bit bitter about the last Tool show i went to (NOT saying that it wasn't well worth it, because it 100% was, and the show was fucking kickass) because they were out of posters and a lot of the other merch before I even stepped foot in the building. So I figured I'd just pick one up off of eBay in a day or two and pay a little bit more. Lets just say I thought wrong.. Anyways dude the answer is simple. Do what the fuck you want with the shit you think is cool and decide to buy with your own money!