I tend to avoid brands like Harley Benton assuming there is not much to expect in terms of quality. But then a friend of mine, a professional musician, recommended the Harley Benton American TrueTone pedal that turned out to be an amazing combination of high quality and low price. And this made me think miracles were possible. So I decided to try this little bass. I had no big illusions and was prepared to tolerate imperfections and do some extensive "tuning" on this 150-euro instrument (like levelling bumpy frets or getting rid of sharp fret ends).
Unfortunately, the bass is so miserably crappy that there is virtually nothing to improve. Build quality and sound are too bad to consider this bass seriously, even if you are buying it just to toy with.
I cannot recommend this product and suggest trying a more respectable brand, which of course will cost you at least twice as much.
Also, I have feeling that there are objective physical limits to what one can get in terms of bass sound from a short-scale instrument. Thus, I guess that my Gold Tone micro-bass whose scale is 635 mm is indeed the lower limit beyond which no decent bass is possible at all (whereas the Harley Benton has 534 mm that presumably do not suffice to reach this limit).