Yes. That's the Mojo. This is Relic's post which mentions the output of Mojo.
Chord and Rob have confirmed many times that the line out mode is simply a digital volume preset, nothing is bypassed. Rob has also confirmed that the 'amp' is basically just the analogue stage of the DAC, you can't seperate the sound from the DAC from the analogue stage in the Mojo. There is no traditional seperate 'amp' section and that's how Rob designs all his current DACs.
don't worry too much, your(our) initial question is to know how much audible difference you get with your ears(not your eyes) between the phone and using it with the Mojo on you specific IEM. so that's the test you have to conduct. beyond that, it would of course be interesting to know what causes what and other tests could help for that. but it's another story.
Thanks for that informative link. So if I read correctly it states that the output impedance of the source(IE: iPod, Galaxy phone, etc) should be no more than 1/8th of the impedance of what that source is driving(headphone, earbud) and preferably less. According to several sites I checked the output impedance of the iPod 6gen Touch is somewhere between 2-4ohms(3.79 specifically acc. to one site which laid out the steps of calculating it).
So that Touch should not have any audible issues driving any of my cans - MDR-7506, HD-280 Pro, DT-880 Pro 250ohm, etc - other than having to crank it up a bit more when listening via the latter-most of those three.
What I was looking more for was descriptions of the effects of impedance mismatch: 'uneven frequency response', 'distortion', etc.
the thing is, several events can occur depending on the amp and headphone used, that are all somehow related to impedance ratios. here the unknown and the number one suspect for audible difference is the impedance curve of
@krismusic's IEM. if that impedance curves moves from very low to pretty high within the audible range, then chances are that the frequency response will be affected audibly simply from using amplifier sections with different impedance output. but then again, if the minimum impedance value of the IEM is above 8 times the impedance of the various sources, then the potential change in frequency response should stay below 1dB and be a nothing burger. so it would really help to have impedance measurements from that IEM. I could do it if he sends the IEM to me, but Kris is being bothered enough already. maybe such measurement will pop out somewhere(perhaps it's already online and I just failed to find?). or if his listening test doesn't suggest much of a difference, then maybe we can assume that the impedance of the IEM is high enough and be happy with that.
some other potential issues purely related to impedance would be when a device has capacitors at the output, then the lower the impedance of the load(headphone), the more the low end will roll off.
in general a really bad impedance ratio can mean some low freq attenuation anyway, but nothing remotely close to what capacitors can do. so usually you'll just dismiss that part as it's assumed to remain irrelevant under usual circumstances.
a bad impedance ratio could also mean bad electrical damping(so how well the electrical signal controls the movement of the driver). if the headphone already has strong mechanical damping, you don't really have to care too much, but otherwise it could result in audible change. it's something you can experience with passive speakers pretty easily as they have really low impedance so it's easy to get a high impedance amp output and fool around with it. with headphones in general I wouldn't expect a clearly noticeable change purely due to lack of electrical damping. and for balanced armature IEM even less so. I've played with resistors to tune the signature of multidriver IEMs when the crossover offered a favorable result(rare), and in my anecdotal tests, I couldn't really tell the sound apart from simply applying a digital EQ with the same FR impact. the only time I did get a noticeable difference, was because my source couldn't handle a very low impedance IEM too well. so adding resistors reduced the demand in current and saved the amp section from distorting like crazy. but again that's a fairly extreme circumstance. even with cellphones, there has been only a handful of cases where the output started distorting horribly into even a 16ohm IEM pushed a little loud. it's something I try to look up when the measurements are available, and the same way, I now avoid purchasing IEMs with impedance going below 10ohm in the audible range, and that is usually enough not to worry about that last situation of the amp itself struggling with a low impedance load.
on the top of my head I think that's about it. if I made a mistake or oversimplified something I hope someone will point it out. the rest is a matter of power efficiency(ideally with impedance bridging, we'd want the amp to be 0ohm), but it's irrelevant for audiophiles. when we look up amplifier specs, they already give the power output into various loads. so we know from the start what's going on and how loud we can get with a given headphone.
It's more of a nickname:
