Based on your use of grammar and display of your abysmal reading comprehension skills, I shall assume that English is your second language and that your comment was a result of a simple misunderstanding. However, if this is not the case, I will, in the following paragraph, attempt to explain my statement and dissect your "appalling logic."
"you are basically saying the BQ of ibasso dap is not improvable whatsoever"
I don't have a single clue where you may have picked up that absurd idea. I merely hypothesized that it would not be fair to assume a mid-level product would have significantly better build quality than its top of the line predecessor released less than a year prior. I know that build quality does improve over time as competition drives higher consumer expectations and new manufacturing techniques are implemented. Yet iBasso has announced no further advances in their manufacturing process and, from what I've seen, build quality has, for the last few years, almost stagnated. It would make sense for iBasso to attempt to improve upon their build quality to remain competitive, but with the current competition not faring any better (namely the Fiio X3 at the moment), such efforts would be wasted.
"if one is not happy with dx100 which was designed few years ago should walk away spontaneously from dx50"
Walking away "spontaneously" would be to do so without reason. Dissatisfactory build quality would certainly be a reason for "walking away" if it does not match others in its class. While the DX50 and AK100 may be on par sonically, one must keep in mind that the two are marketed to two different groups of the audiophile community. The former is attempting to be everyman's high end dap, akin to the Chevrolet Corvette. The latter is a luxury item which, in my opinion, is outrageously overpriced and offers unremarkable sonic performance with regards to its formal competitors; a Maserati GranTurismo to iBasso's Corvette, if I may continue with the automotive references.
"they could never keep abreast of advacement of technology"
I didn't say that.
"you sound like an avid fan of ibasso, but this is how you defend them"
Au contraire, my dear friend. I have never owned an iBasso product and may never will. I am neither defending nor assaulting iBasso; I sought to help you better rationalize your concern. If you believe user interface and build quality of a company's premier product, their pinnacle of engineering, to be "junk," them maybe you ought to wait for something else.
"the thing is, is it really that hard for these chinese audiophile dap manufacturers to improve these objective aspects of their products in stead of constantly boasting the subjective notion - 'sound quality' "
Companies exist to make a profit. With certain material costs and wages rising rapidly in China, it is becoming increasingly difficult to maintain the wide profit margins historically enjoyed by Chinese manufacturers. iBasso has their sights aimed squarely at the audiophile market with the DX50. It is far more profitable to increase subjective sound quality than to improve build quality and user interface. Better build quality requires more intensive manufacturing processes and hours of extra engineering. The same goes for user interface; for any tangible increase in function, countless hours of programming are required, even for what consumers may consider to be "simple" functions. On the other hand, changes in subjective performance may be achieved through the swapping of different parts or "tinkering," which is vastly cheaper and easier. I know that I am vastly oversimplifying the process; a great degree of credit is due to designers for their creativity and ingenuity in their implementation of various audio circuits.
"Therefore, it would be either a shame or an intended scam for ibasso not to improve these deficiencies to make dx50 more portable"
I applaud your single proper use of capitalization; my hat goes off to you. You keep on forgetting whom iBasso is trying to please. Most audiophiles place subjective sound quality above all else when considering a given component. If the DX50 sonically outperforms its peers, then it will be successful in its intended niche. If it is no better in any department than a Sansa Clip, then...I suppose you may be right on this one. But I have the slightest feeling that won't be the case.
