I finally got a Boss Katana 50w 3 weeks ago. I ran an mp3 full blast for a week and it made a huge difference to the internal speaker, not shrill/bright anymore.
I have to say that I'm having a lot of fun with it, sounds good, feels good and perfect for grab & go jam: 20lbs and only a dual footswitch that fit in the bottom of the combo.
I tried it with an external cab (2x12" loaded with Celestion G12K-100) and sounded even better.
The secret ingredient is the master volume that needs to be full cranked, then start dialing your sound from there using the power attenuator to manage output level.
The Katana is an amp, not a modeler, and needs to be regarded as such: you like Roland (Boss) sound or not, same as other manufacturer (Vox, Fender, Marshall, H&K, Mesa, etc.).

Incredible the sound I'm getting from the Katana and my LTD ST213 (used) for a total of $400.