Actually, I compared Atoll IN200 and Stello Ai500; both are musical, balance and powerful. Personally, there is no much difference to me as comparing Atoll 200 and Stello Ai500. However, my target is Atoll pre-amp + power amp. I don't want to change from int amp to pre+power amp in future. So i'm still saving money at this money. It's just my personal feeling. I advise ching to try both amp by yourself. Thank.