I have had two of these over the last 9 years. They work but are built so poorly that you have to be very careful with them. The CD door is the achiles heal of the unit. They also could have cut some cost originally but not bothering with the effects and tuner. The basic function of cutting the baseline out works well enough for the unit to be useful and the slow down function also works. The sound degradation with the slow down down function is there but I haven't experienced it being so bad that the function is unusable. The bass elimination also works with mp3's run in to the " line in " jack but you cant use slow down or looping. This is how I use mine these days. I tun my iPod in to the unit. Tascam came out with an mp3 version of these years ago but I guess the discontinued them. Seemed like a right move as CD format has been on the way out for 10 years. I'm sure there's an app out these days that can all of this now. Over all the unit can function at its basic job but I'm sure there are better choices on the market now. I wouldn't recommend buying one of these unless you get it for under $30.00.