When off, you have a buffered bypass that don't change anything to your sound. The XLR outpout for DI works correctly.
When on, you have low, high and volume controls. They do the job, no more no less.
The mix button allows you to blend in 3 things:
- the drive (gain), I'm not found of it, I prefer a separate OD pedal.
- the harmonics, it's sort of presence control. I use it just a little because it enhance the background noise.
- the tubesim, no button to control its level (only the mix one). I like it because it warms up the neutral (almost flat) sound of my combo.
I was glad to have it in my bag when the amp suddenly shut off. It's not Darkglass nor Sansamp sound but it does the job and can stay neutral when off.
Cheap enough and small enough to carry around in case you need a DI outpout but not for professionnal recording.