Listening fatigue

Ah, that insidious crescendo! I think you're right.

Harri009 makes a very good point!

Agree that clipping is a likely significant factor with most any SS amp of that power rating and most better modern smaller speakers.

The sound travel 1000 feet per second. You can hear the sound from speakers for 4th of a second and the sound will travel 250 feet. Your room is 15 x 20. Every sounds from speakers will bounce walls and hit your ears more than 10 times. That's no good! I don’t know if your room is sonically live or dead. If it’s live, you need to tame your room. You need to reduce the sound reflection.

I recommend 1) Madisound Dampers: Felt Defraction Ring for Tweeters. Put these $2/each felt ring on tweeters of Mites. These dampers will reduce some early reflection sound from speaker cabinets. 2) If the room is live, put some Auralex or sound absorbers on walls. If possible put some damper on the ceiling too. If your wife think they are ugly, put some pretty curtains on walls instead. Good luck!

If you get rid of early reflections, some imaging information will seem to be lost. This is because the ear/brain system uses early reflections to assist in image location.