I am currently using a pair of bookshelf size speakers that are 12.5" in height. I am planning to get a nice pair of stands. My problem is the stands I can get at 27" or 28". I am not sure what height is best. The 28" maybe correct for now, but if I upgrade speakers to a larger pair of bookshelves they maybe a little to big. So is it better for the speaker to be a little higher or lower?
I'd err on the side of caution: having tweeters ABOVE ear level is not bad and sometimes even desirable (like if you have high ceilings for example) but if they're BELOW ear level the sound will definitely suffer.
That makes no sense. Above or below; what's the difference? And what do high ceilings have to do with it? There's more energy reflected off the floor than the ceiling in terms of distance from the driver. It is always dependent on the vertical dispersion of the tweeter. If the high frequencies miss your ears, it doesn't matter whether they miss above or below your ears. What matters is they missed.
The point of my earlier response is, if you get new speakers that are significantly larger than your present speakers, then you should also buy new stands. Keep the tweeters directed at ear level unless the speaker manufacturer should suggest otherwise.
Do you worry about what size tires to buy also? What if you trade cars before their worn out.
You buy the equipment that goes together to make the system work at its best.
A 1" difference in the stands you are now considering is not enough to concern yourself with. Just sit up straight and you won't notice the difference.
When I first placed our 602's (rear surround positions) on stands I took note of a reviewer who suggested 45cm stands were best for 602's to place the tweeters at ear level. What we discovered was (a) they were below our ear level - so the reviewer must have been vertically challenged - and (b) much of the sound was being absorbed by the rear of our sofa. The exchange for 60cm stands did wonders for the sound though the tweeters are a couple of inches above ear level (same applies to the front 602's) if we slouch. Which we we do. We are slouches. We slouch on the couch. Sitting up straight only lasts so long. LOL!