Since you are focused on closed-back headphones and you liked the sound of the EL-8, check out the EL-8 closed version. If you are using an iPhone, you may want to consider the EL-8 Titanium which comes with the Cipher cable which has a DAC and amp built into the cable and plugs directly into the iPhone's lightning port. I have a pair of these, so you can try them out if your dealer does not have it.
As
@sheldaze stated, it does get interesting when you're trying to find an all around headphone because there are competing interests with mobility/convenience on one end and uncompromised sound quality at the other end. Because of this, many of us have multiple pairs to accommodate our needs (ok, this is only one reason we have multiple pairs, the other is that we have a problem
).
When you say for use with a mobile device, does this mean usage on the go or usage in the office or your home, but not at a desk? I ask because there are headphones like the MrSpeakers Alpha Prime that are closed-back and can be used with tube amps (they actually pair well with tubes) and can be used with mobile devices with a mobile amp/DAC, but would not be good to use on an airplane. Kind of large for that.