Speakers sound too bright.

You mentioned that your room is 30' x 30'.  How high are your ceilings?  That is a large volume of space.  I think you might find that this has as much-or more-to do with the loudspeaker's interaction with the room, than it does with the loudspeaker itself.  A square room is going to have more pronounced standing wave issues at certain frequencies where they double up, due to the even dimensions.  Go to https://realtraps.com/modecalc.htm and download the ModeCalc and plug your dimensions in and see what you get.  It displays the first 16 axial modes up to 500Hz.  With your dimensions you will see what you are up against and can start making better decisions about what you will want to own. 

I would think it's primarily between your ear and the speakers. If they sound too bright, your ears are telling you what you may not want to hear, no pun intended. I would not tweak anything, but return the speakers. 

Or you can buy and EQ, quickest and cheapest trick.

I purchased a pair of Zu Soul Supremes and had the same issue. I waited for break in and went past the return date. I never got over the fatigue and ended up selling them. Was able to listen to Audio Note e/lx and problem solved. I don’t blame Zu, since I know they make a good product. I think I have sensitive ears is all. Don’t make the same mistake I did and hope they work out. Try to break in and if they don’t get significantly better, return. No shame. 

You need to treat your room. Absorbers for high frequency 

preferrably behind them.  Will help a ton

good luck

One possibility. If these new speakers are 2-3db higher in sensitivity you may be playing them louder than the Kefs not realizing you need to lower the volume. Louder than normal levels can make mids and vocals a bit sharp or harsh.

Happened to me once. Upgraded speakers. Was testing them out on familiar music, but not remembering that I should have reduced the volume about 35% due to 3db increase in sensitivity. Once I realized this and lowered the volume I was very pleased with the sound which had sounded occasionally bright or sharp when I had the volume too high.