Thank you for your positive feedback on N3. I don't exactly have an scientific explanation but I do agree that N3 will sound better after 1 week of regular usage. I have experienced that myself, and several members of this thread has similar observation.
The ATH headphones are well-known for it sweat female vocal, but bass response is not its strong suit unless you are going for DJ or bass-head targeted models such as ATH-M50x. The closed wood cans can offer lots of bass relatively, but they aren't the headphones that I'll recommend if you are looking for linear, articulated, and punchy bass response. I am not sure if you are really should go for the basshead cans. From what I read, you are more bass from your ATH and something that can go lower. I would suggest you to add Meze 99Classic to your candidate list, or 99 Neo if you need something to compare against the JVC at similar price range. I haven't heard the 99Neo yet, but the 99Classic was one of the most loved headphone with Cayin DAP since I collected them at Munich High End Show 2016.
Regarding the video delay issue, I can basically claim that the problem is inevitable because N3 is using asynchronous usb transmission. I shall quote the following
explanation on asynchronous USB for discussion purpose:
I would like to draw your attention to two issues:
- the DAC’s master clock isn’t synchronized directly to any clocks within the computer
- This clock controls the datastream from the computer to a buffer near the DA converter
In other word, the audio signal processing is deliberately "disconnected" from the computer clock but the video display remain connected to the computer clock, so the video and audio are not synchronized by nature. In addition, we need to create a data buffer in the audio circuit in order to hold the audio datastream from the computer, and the buffer will inevitably caused delays in the audio signal with reference to the non-buffered video signal.
If you must achieve audio and video synchronization, you can only do that by adding a delay in the video reproduction. Most Home Theater system will have to handle similar issue and they call it lip-sync, this can be a DSP feature in the Audio-Visual Control Center (Receiver) or a video delay adjustment in the LCD TV or projector, so please check your computer monitor to see if similar feature is in place.