BOSSKTN-110B KATANA-110 BASS, Versatile combo bass amp with stage-ready sound and advanced features,Black

Second one I have purchased from Amazon and is faulty out of the box

This is a bass amp essentially with a built in multi-effects board. There are a baffling array of controls and it is not entirely obvious what they do, and the lack of a display screen means that it is a bit tricky to understand what is going on.My recommendation is that fairly early on you get a PC or Mac attached and use the Boss Tone Studio for the Katana Bass and then you can see what is going on.You can use it out of the box, but the manual is a bit thin on hints and tips. Here are mine:1) Set it to flat and switch off effects. Have blend set to 50%. Set both gain and volume to about 9 o'clock. Unlike a guitar amp, using high volume with low gain still gives distortion.2) 1 watt is not 1/60th the loudness of 60 watts - it can still go loud!3) Use the PC app to understand the effects like drive and FX. As there is no display on the amp, just different coloured lights. So for example, depending on what preset or bank you use, the compressor AND drive is a different effect. Similarly, the effects are completely different depending on whether there is a red, green or orange light set.4) It is not obvious that the display lights are switches. Similarly, there is no off and on for effects, you have to set the control to zero to switch them off.5) Without the app, you can't set features of each effect, so reverb you can only increase the volume of the reverb, whereas with the app you can set reve4rb length, tone etc.6) If you use presets, the current settings are not the same as the knob positions.7) Using the app connected via USB, it is very easy to control and understand how it is set. My suggestion is that if you understand amps and effects, the starting point is to set up channel 1 bank A as a starting point with a mild compressor setting, no drive, lowish gain and volume, 50% blend, tone controls more or less middle, FX off but set to something useful like mild octave (less than 10%) and mild reverb (e.g. default plate 20%) and have that as your safety net.8) The back panel is comprehensive with additional send and receive loop and a proper selectable DI to the PA independent of the amp master volume.So, all in all, the warning label is, if you don't use the app, you are never going to be able to use the effects properly, unlike a Line 6 Spider guitar amp for example, where it has a small display which might be fiddly but at a pinch you can select and even edit effects. The app is easy to set up and use if you understand how guitar effects work, and the effects are generally emulations of the existing well known effects so you can try and find the originals to get an idea of how to set them, however, like many multi-effects emulations, Boss are a little hazy on what they've actually copied, so if you are a beginner, it is not always obvious how to set the effects. To be honest, that's not a lot different from any standalone pedal board.If you don't want effects, then perhaps look elsewhere for a simpler, lighter cab, but if you want something that can be used at home for practice and recording, used in a rehearsal studio up against a real drum kit and in small pub venues or with the support of a PA system - anywhere, this has a wide range of uses.