The Project Ember is an effective amp, ill probably roll with them. I gathered they wont cause much distortion or altered effects with even denon 5000s while allowing for upgradable room if the AKG K712s ever need replaced with some harder to drive headphones. The different voltages and gains are interesting, the Asgard has no room for play and gain levels cant be changed without accessing the xonar essence stx control panel. Tube amps are a new experience, the Project Ember seems to match K712s strengths with maybe even helping out the mids while keeping a warm sound of solid slate amps
The project ember doesn't really have enough distortion to be audible, although some tubes may make it have audible distortion. There is a certain point where distortion levels become meaningless in amps and many SS amps and tubes amps can reach so low distortion that distortion won't impact the sound in any audible way. Some tubes may increase distortion, but some tubes have almost no distortion. Differences you may hear from good tube amps compared to good solid state amps are most likely attributed to amp design and the fact that tubes and SS are a different method of amplification so they can have their own sound character that isn't related to distortion. Sometimes the difference is so little between tube and SS you can't really tell a difference. The biggest difference I found to be the case with tubes and SS amps in general in terms of sound is that tubes have a somewhat different presentation of sound than SS amps, tubes generally sound rounder and have more body to their midrange from my experience. The Project Ember will probably be a really good amp for the K712, the question is how good the stock tube is for the K712 and what tube would likely be the best for the headphone. The K712 can really sing on the right system.
I found the FiiO E12 to pair well with the K712, it's a combination I am happy with. It's a good choice for the K712 for the price.
Edited by kman1211 - 6/1/14 at 6:16pm