tire noise from cupping

had a subie dealer check out some annoyingly loud tire noise a few months ago and they told me my tires were cupped. had them rotated and balanced and was told the noise would go away after a few thousand miles once the tires had worn down.

>3K later and the noise isn't much different, so i took it to an independent shop that told me i'd need new tires to get rid of the noise. they said they couldn't find anything wrong (suspension, wheel bearings, etc). i figure the previous owner just didn't rotate/balance them...

anyone else have problems like this? i'm considering new tires b/c the noise is driving me nuts.