Why do my ears ring with my new amplifier?

Do your ears ring when no music is playing but the equipment is on?

I've never heard of this problem. It may be a high frequency oscillation in the amp/system combination or the amp may have a fault.

Unplug everything except the amp and speakers and turn the amp on. Ringing? yes, there is a problem with the amp. No ringing? Plug a cd player (any cd player) into the integrated amp. Ringing? yes, amp/system oscillation problem. Again, problem with the amp. No ringing? may be your streamer.

test each component connected separately.

Also, it may be a time of the day issue where you are getting noise injected into your system through your electrical system that may have been blocked by the previous component, but not by this one.

One thing at a time

"My setup sounds great when I'm outside of my room. When I walk in and sit down, my ears start ringing."

This shouldn't be too much trouble since you have small speakers. Move your system to another room and try it there. You don't have to invest a lot of time in setup, you just want to see if the ringing will go away in different environment. Along with some of the others, I'm not too sure what the problem is here. Given that your room is fairly small, its going to be essential that you figure if the problem is equipment related, or possibly the room.

If it turns out that you still get the ringing, I think you should look at your source. I'm not too familiar with your Lumin, but with computer audio related components, there's usually a lot of adjustments and choices. Since you are plugging it into a new preamp, you could have a gain related issue, or something similar. It may need to be reconfigured to work better with your new integrated.

Tape some tissue paper over your tweeters just to make sure it's not excessive energy in the 2-10 khz region.

Listen at lower volumes for two days. If your ears don't ring, then you have been playing it too loud, like being at a rock concert or any loud venue and coming out with ringing. This is part of incurring noise-induced hearing loss, by the way. Tinnitus can become permanent with continued exposure to loud noise.

The spl meter idea is a good one. If things are going well you might not realize how loud things are.