Another interesting function. Restorer of poorly encoded mp3s. Its quite different than usual. It has three settings 64, 96 and HQ. Restorer should take care of quality loss caused by poor compression of mp3. This is quite usual feature in all receivers, but in most causes you can hardly hear any difference between original mp3 and "restored" one. In case of Denon, it also tweaks bass and highs and the result is surprisingly audible and good.
I have to say that I am sending most of the music over optical cable from my HTPC. I am using J River Media Center 13, which is able to send audio in the same form as it was encoded over WASAPI driver, so Windows cannot even touch the signal (which they normally do), so the receiver gets pure 16bit /44kHz signal untouched by anything (windows mostly resample the music to 48kHz, which means, that there is some loss and receiver then converts it back to 44 which is another loss).
All my mp3 files are of very high quality (at least 192, but mostly 320kbps VBR), but when I select Denon RESTORER, the sound dramatically "improves".
By that I mean, that it has more depth, bass is richer and the sound is smoother. It may be a gimmick from Denon, as they could only apply some EQ settings and call it RESTORE, but to me its quite pleasing difference from the original.
This may be a minus or nonsense for audiophiles running PURE DIRECT in perfect listening rooms, but to me its quite nice improvement in the resulting sound.