Who makes speakers with relaxed high freq.?

Dynaudio Contour S3.4 should fit your bill perfectly. Dynaudio makes arguably the best tweeter in the world.

Yes that would be speakers that use the Seas'.

Spica TC-60s and Martin Logan Aerius i's. I have both. Both have slightly rolled-off, non-fatiguing but nicely detailed treble. The Spicas are a bit more rolled-off than the Aeriuses. Both offer superb imaging. I've added a Behringer DSP8024 digital EQ to the Aeriuses, and it's brightened them up substantially, as well as smoothing out and extending the bass response. I like the EQ effect, but you might prefer the Aeriuses straight up. Got my five-year-old used pair in excellent condition for $1,000. My living room is pretty bright, with sparse furniture, plaster walls, and a rug over a hardwood floor.

Very tricky, you want small, good bass and smooth!
Sonus Fabers family would be ok, used of course, spendors are ok....these are very general answers of course....but get a pair of Ribbon based speakers and dont come much smoother than that, dont get duped as well sometimes.

I tried the some chinese ribbon design and they were bad...like really bad, bright and brittle. So design choice is vital, try a pair of used Apogees, you will die and come back alive. Its that smooth and detailed. Never hard on the ears ever not matter what the recordings are, even the original Queen stuff sounds good so.....

Good luck

You have received excellent answers to your question as you asked it. There are other problems that can create harsh bright sounds coming from your speakers. Cd player/ preamp gain mismatch comes to mind. Not saying thats your problem but take your time and think about causes from all angles as the posters mentioning cables have inferred.