What about sound quality? Compared to plenue D or other players in similar price category?
Don't have the Plenue D anymore so cannot make a direct comparison.
SNR is comparably good, from memory. The Plenue J is definitely among the rather quiet DAPs when it comes to hiss with extremely sensitive IEMs - not as perfect as the Plenue 2 or iBasso DX90, but still good.
Sound is subjectively more on the smoother side. Definitely perceived as more "impactful" and smoother compared to the DX90. Staging not as wide as the DX90 but deeper and therefore more circular. Transparency with sensitive, well-resolving in-ears about on the same level, but as mentioned different in presentation (DX90 slightly more clinical, Plenue J a little smoother).
Low output impedance confirmed. Also no bass roll-off with low impedance loads.