I use these preamps predominantly on drum close mics and they do some magic when you drive the signals into the transformers using the Tone function. It's a great way to tame peaky snares and their ilk and round off the edges. I've also used this preamp in cleaner ranges without the Tone (eg., on condensers I prefer this switch to be off) and it works fine in these applications as well. Great as a bread and butter set of preamps, I have two units for 8 channels total.
I did have problems with a faulty unit being sent in the initial delivery, but Thomann replaced it a little later with a perfectly functioning one, no quibbles at all! The staff at Thomann was very helpful and friendly throughout the return procedure.