First I found coax cable caused sound intermittent disconnected. After I have taken a closer look and cable copper partial broken which will be needing replacement.

  Hi Paul, my coax cable which came with DX90 got issue, how to get replacement ? thanks,

Based on feedback here, I will update the firmware 1.4.2 and test more Coax output, please ignore above test results about 24/96 and 24/192 and it looks results vary.

I mean coax cable came with DX80 and DX50 .

I used the optical cable came with DX80 by iBasso.  I tried my DX50 optical cable also, the same results.

  I have just tested my DX80 with 1.4.0 and Sandisk 200GB + 128GB. DX80 output  the optical port to Onkyo Atmos Receiver or Onkyo older 636 like below.   1. MP3 , or FLAC, ALAC 16/44.1 , 16/24/48, 16/24/88.1 working fine. 2. FLAC 24/96 sound distortion and sound disconnected. 3. FLAC...

For my DX80 ( first batch with Firmware 1.0, right now 1.4 ), any DSD ( No sound)  , 96KHz ( distortion) , 192KHz ( no sound), cannot pass through Coax. Only 44.1 and 88.2 KHz. I do not know other people. I heard coax not for Hi-Res music.

I only listen Hi-Res (DSD, 24/48/88.2/96 above) only, no 16/44.1 and below. I think EQ does not make any sense to me. I installed 1.4.0 firmware, re-scan, no issue so far.  SD cards : Sandisk 200GB + 128GB  FAT32 . Please check below if you have issues. 1. check your SD cards. 2. format SD...

I think EQ only works for headphone out  with 16/44.1 only, and not for Hi-Res (DSD, 24/48/88.2/96 above).  No matter how to adjust the EQ, I cannot tolerate the sound distortion ( maybe colored sound)  because of EQ. EQ is useless for me because sound is not real.

Loaded FW 1.3.0 and found volume lower than before.   Wallpaper still there.  

I am think about converting DSD files (DSF, DFF) for DX80 to FLAC 24/88.2 for 2 purposes, one space saving and second for optical output. 1. Do you think any sound quality loss noticeable if DSD->FLAC 24/88.2 ? 2. If it is worth converting, for best sound quality, convert by Foobar2000 or Korg...

  OK. We should pay respects to all different points. Can all of DX80 owners list 3 reasons why you buy DX80 instead of other players based on your needs? and list what you are listening ? Hi-Res (DSD, 24/96-192 FLAC) , Standard lossless (16/44.1 FLAC/ALAC/APE), Lossy files (MP3 320K, MP3...

  I saw your points, but I only use DX80 for Hi-Res only (DSD and  24/96-192 FLAC). I think the DX80 big selling point is native DSD playback. For regular CD quality (16/44.1) , I am using iPhone 6+ or streaming from 2TB hard drive. As for sound difference between DSD, 24/96 FLAC ,16/44 FLAC...

I got confused. If RockBox cannot support high-res file type, why bother RockBox ?   If you do not listen hi-res or DSD, why bother DX80 ? DX80 was labeled with HI-RES.

I have tried , it is not working for iPhone 6plus with CCK, not working for iPad 2 either. Maybe not Apple certified.