putting speaker vertical or horizontal?

Never put speakers horizontal, unless they're designed to be put horizontal.

And don't buy speakers that are designed to be horizontal, either.

NHT's speakers are designed to work in the vertical position. The placement of the woofers and tweeters on the speaker baffle does dictate how/when/where the sound will reach you. Placing the speaker on its side does change that. If you care to search through Audio Asylum, there are threads about how the D'Appolito array (typical horizontal center channel speaker) is not all it is cracked up to be.

If your room set-up demands a speaker to be placed on it side and it sounds OK though, why should you care? If the option is no music in the room ... you can live without the entire audiophile creed intact. This a hobby that does welcome experimentation. For a while though, I did use my NHT SB2's on their sides and quite frankly, they sounded pretty good.

Regards, Rich

Horizontal is no good, it wont produce the stage well and you will have alot of vertical wave constraints.

I remember I had a pair of AR-12's, and they even had the logo on a post on the front, so you could swivel it for horizontal operation. I tried it once. Just once. They sounded awful.
YMMV.
John