I understand SACD and CD ISOs.

Thanks for the update, iBasso.

Many thanks for the firm Ibasso.

  Great news. Many thanks Ibasso.

  Try to download the last version again and reinstall the drivers. The last version doesn't have problem with the certificate, I am using Windows 8.1 and this problem doesn't happen.   And Tidal doesn't recognize the DAC because the drivers don't work correctly.

  Yes, rockbox supports replaygain.

  In my case, using Linux, by the moment I made the update without problems.

    Amazing. 

  Congrulations.   I can't help you with the other topic. :)

  There Is not cue sheet and they are ripped from CD.

I think I  detected a bug in RB. When I play X - Ed Sheraan in FLAC format, RB plays only the first 10 seconds of each song.    However it plays without problem in Mango from the same SD card. 

  I also perceived a lower volume but it is with replaygain active and files with this tag. It is the same case, Rockbox have an option to up the volume automatically for those files.

  The rockbox is in another file, you can download the last version from: http://napych.com/other/rockbox-for-ibasso-dx90/official-rockbox-binary-builds/ Or this post: http://www.head-fi.org/t/727669/rockbox-for-ibasso-dx90-dual-boot-with-mango-stock-firmware/795#post_11534257

  I used it and it works without problem.   You have to copy the .rockbox to root of internal memory and copy the update.img to same place. Then you select Settings -> Advanced Settings -> Firmware update.   It installs the firm and after the reboot, if you place hold on appears a screen to...

  Many thanks, it worked without problems.   I deleted apps and rocbox folders and copied .rockbox.