Looking for feedback on whether to buy Audeze LCDX or Mr Speakers EtherC

I would just say that as with any TOTL headphone, the better the amp (and DAC), the better the sound.  The Ether C is reasonably efficient -- even an iPhone drives it using max volume, and a good portable amp can do a very good job. Do mean the Fostex HPP1? If so, I had one and it is a very good portable DAC and amp -- should be fine with the Ether C. For a portable DAC/amp I'm using a Chord Mojo and the sound with the Ether C is amazing, with enough power to play so loud you would damage your brain let alone your ears.

Why did you get rid of the HPP1? What's better about the MOJO? And do you have a separate desktop dac/amp also? Does the MOJO accept an iPod? That's why I got the Fostex...it has the USB input. 

Sorry for being such a newbie, but this stuff is fascinating and I like talking to people with a similar obsession for good sound and music.

I sold the HPP1 not because it wasn't good -- it was very good - but because I wanted what was considered the best at the time (3 years ago) - separate amp (ALO) and DAC (Cypher Lab) using an iPod as a source. But the Mojo is better than all of them. iPod cannot be used with Mojo, a separate "transport" is needed, such as a DAP using the digital out into Mojo. Suggest you look at the various threads in Head-Fi, but there are many and it's much reading. 

Correction: An iPod can be used as a source with the Mojo provided that the iPod has a lightning connector, such as the iPod Touch, and not the older 30 pin connector, such as the iPod Classic. That is, an device with the 30 pin connector cannot be used with the Mojo.