Yes, the line out isn't touched by the E10K's amp.  I used to have me E10K's line out running to a lepai amp for my speakers and it worked perfectly.

This is all I want to know.  I have the 598's at work and use the K7xx at home... but for 100 bucks this has my interest peaked.

I listen to music through spotify and google play music, o2/odac on the K7XX and enjoy the experience quite a bit more than with the 598s.

I picked these up on the first drop and paired with my O2/ODAC they sound fantastic.  I've left my HD 598's at work permanently and love coming home to these.  I want to try different types of headphones, because when I only had the 598's I was sure that was the sound profile a liked, and now I...

Go Fiio E10K IMO.  I haven't used the SMSL, but I am currently using the E10K at work and still love it.  Benefits over the SMSL include bass boost (if you like music that benefit from it, the switch helps quite a bit.  The other big one for me was a line out for speakers that lets you keep...

  Well keeping the amp set too low can introduce imbalances in the channels from what I've been told.

If your system is too loud on 1 with low gain, turn down the system volume in your computer so you can turn the amp up a little more.

Are there any tests showing one way or another that cables impact sound?  blind a b testing? 

  From what I have read, the idea is to keep the dials away from the extremes.  I usually try to keep it as close to half way (5) as possible.  If low gain at a 9 gets you the same volume as a 4 on high gain, use high gain.  Similarly, if a 2 on high puts you where a 6 on low would be, use low...

Check out JDS, their customized O2/ODAC allows you to select a rear power jack for an extra 3 bucks.  Looks snazzy on my desk.   EDIT: Link http://www.jdslabs.com/products/48/o2-odac-combo/ 

The front facing jack like the headphone jack?  

I tested mine by listening to music about as loudly as I could stand for a few seconds and then turned it up just slightly more to test.  I don't care if maxed out it rattles because I wont ever hear it at that volume.  I feel I have reasonably tested mine to not rattle in use and that is good...

Unfortunately no.  I am pretty new into the audio scene and this is my first AKG.

Awesome.  I am using these out of an O2/ODAC and have been enjoying them very much. I was using the HD598 previously and the bass alone has made watching tv/movies very enjoyable.  I am looking forward to spending more time listening to these headphones.

Any downsides to the bass port mod?  I just got my K7xxs so I want to enjoy them as is for a bit but I am interested.