The Yamaha THR-5 is a very well built stereo 7 watt amp that has software that allows you to connect it with your computer so you can craft various sounds. It is all metal and built like a tank.
At $100, the Katana is a superb deal with surprisingly great mid and high tones – and perfect for guitars. I found it not so great for my electric cello – low tones sound like a cheap transistor radio or a small mono cell phone speaker. The build quality has a very plastic feel to it.
In some ways this is an unfair comparison, but they are both 7 watt amps that can be used for practice. The Yamaha is a superb amp to mic. I have a Shure SM-57 with SE Electronics “Dynamite” preamp and a Royer R10 with dBooster. These mics love the Yamaha, but for Cello on the Katana its just not a good fit the sound is a weird muted and muddy sound.
When I first played my guitar through the Katana I thought it sounded better than the Yamaha, it was more “raucous”. So, just as a guitar practice amp its killer for the price.
For my recording – it will be the Yamaha for every instrument I play.