is there a reason not to use a boost convertor in a cmoy?

i see people recommend having two 9v batteries so it'll have an 18v supply which will give you more cushion space for non ideal stuff going on. is there any reason not to have one 9v battery and a boost convertor to give you a higher supply voltage? all i can think of is shorter battery life.

i ask because i want to build a cmoy for use at work, but i dont want to deal with batteries. buying a wall wart to use as my supply pretty much doubles the cost of building the cmoy though, so i was thinking of powering it through usb, getting 5v and running that through a boost convertor to get a higher supply voltage to power the cmoy. is there some fundamental reason why this wouldn't work or would be a bad idea that i'm overlooking?

@avro: i'm pretty sure (not 100%) that a cmoy + boost convertor shouldnt draw anywhere close to 500mA, so i should be good there. none of my friends are into diy or anything like that, so none of them would have any wall warts for me to get for free. and yes i do realize they are pretty cheap to buy, but considering how cheap the cmoy is to build it'd be pretty much doubling the cost of the build. and a wall wart is a lot bulkier than a usb cable to carry in a laptop bag or something like that.

@cobalt: thanks for that link

heh well yeah after thinking about it i realize it probably wont be any cheaper than a wall wart, but it'll at least make the build more interesting than just doing another cmoy

plus i dont like wall warts. they're fat and cover up other spots on the power strips i have >:[

what did the carrie amp eventually flesh out into? i see from the first post that it was going to be a usb-powered three channel cmoy, did it change somewhere in the 55 pages of that thread? and out of curiosity, can someone link me to a good source for reading up on the mini^3 and what it has over the cmoy as far as design goes? what the hell i might as well go the extra step in derailing this thread now and ask, what other diy amps are there on the cheaper side? i can't imagine something cheaper than the cmoy, but i'm open to anything up to maybe like 50 bucks for parts not including power

hm, found the mini3's site at amb, from the looks of it as far as signal path goes it just has a buffered ground channel for difference from the cmoy; power supply will take me a bit longer to see what's going on in there

edit - oh hey if i scroll down there's descriptions for the different parts of the circuit lol.

what does buffering do for each channel? i get what the point of the active ground is but i havent seen any explanation for buffered channels as of yet is it a different method of eliminating crosstalk? also, what do you mean by "tightly integrated" for the pimeta?

so it helps with driving heavier loads but doesnt really make a difference for a smaller load right? if that's the case i probably won't bother, i'll probably stick with my usb powered basic 2 channel cmoy that i had in mind at the start