Had the iFi iCAN SE for a while now. It pairs very well,with the iDAC2. The only thing i don't like,is having to turn it over, for the gain switches.

Yeah, that's a slight inconvenience though it isn't too hard to do :} At least one doesn't have to open it up.

"However, in practice they turned out to be mere convenience extras, sounding like average treble and bass boosts respectively. The issue I take here is that most of these features are touted as technical marvels that in reality never actually happen and represent something that does not justify the grand words put behind them."
 
With reference to the above sentiments regarding the XBass and 3D effect, I couldn't disagree more.  My primary use of my Modi 2 Uber --> iCAN --> JVC SZ2000 is for gaming, and then movies/music.  However, I do listen to music for at least 4 hrs a day while at work, and am an accomplished pianist, so please understand that I have deep love for music.  The fact that I primarily use my system for gaming should not have significant influence on the relevance of my thoughts below regarding the application of XBass and 3D to music.
 
While I can understand how XBass on its own, i.e. no EQ, is relatively modest, when sub-bass EQ is applied the XBass scales with it, producing a monstrous and fantastically deep and clear bass boost.  With good EQ software, the XBass switch becomes much more effective and let's you not just hear the bass frequencies, but feel them.  The sensation the bass boost on the iCAN delivers with proper bass cans and EQ simply cannot be marginalized.  My favorite basshead quote is that, "it's not what the cans do, but what the cans can do".  With respect to this, the bass boost switch when paired with digital processing and top ten basshead cans, the XBass does deliver on its promise in a way that can not only be heard, but truly felt to the core of one's being.  
 
Additionally, I can attest to the fact that the effectiveness of the 3D switch is largely dependent on the headphones.  The iCAN didn't do much for my PSB M4U2 in this regard, but it makes the soundstage of the SZ2000 absolutely massive, especially for gaming and music.  When I first used it for Star Wars Battlefront I was totally blown away by how wide, deep, and precise the audio experience correlated with the visual.  The positional accuracy, clarity,and separation of the sounds is astounding.  This same effect is also applied to symphonies.  Some of my all time favorite pieces are Chopin's piano concertos and the 3D mode is very effective at improving the soundstage and bringing forth instruments that may otherwise be drowned out.
 
To summarize, the effects of the switches are largely dependent on the application and source.  With EQ and headphones that have a lot of untapped potential, the iCAN is an amazing piece of equipment that can tap into said potential and bring out the best of both the audio and the headphones.  "The issue I take here is that most of these features are touted as technical marvels that in reality never actually happen and represent something that does not justify the grand words put behind them."  I am a firm believer that said grand words are absolutely true, and I do hope that iFi continues to...

...to market them as such because they were a major selling point for what has been one of my most enjoyable purchases of all time.

@227qed "I can attest to the fact that the effectiveness of the 3D switch is largely dependent on the headphones.  The iCAN didn't do much for my PSB M4U2 in this regard"
The former I agree with, but the latter all I can say is really? With my M4U 1 both the 3D + and - effects are very noticeable. The M4U 1 already has a huge and open soundstage, rivalling my HD598, but with the 3D + they utterly decimate them. 3D + with my HD598 on the other hand does virtually nothing except add a touch of treble. The same goes for my SR60e. Regardless, yes, the 3D is very headphone dependant.

Nice review!

Interesting, thanks for your thoughts @227qed. I do can see how said effects can help colored headphones or systems. However for a neutral system,they did not do anything good. Part of the reason being that they are not subtle, which does not bode well with reference sound tweaking Gaming is also a very specific application but as an avid gamer I can see your poinr.
Glad you liked it @Bansaku. Thank you

Great review conquerator. Thanks for comparing it against the Liquid Carbon. Considered the iCan SE but wondered if the Tubestate tech was worth it (added the iTube to my desktop instead). Figured the SE would sound similar and better without being a huge leap above my iDSD Micro.

Thanks @gr8soundz !
It is a great little unit.

I have an IDSD already and wanted to give a little bit extra in terms of headphone amplification compared to the iDSD which is very good but I think the DAC is better in my setup. I have the SE driving my Ether Cs and it does a sterling job without gain so for the moment and until I can get the amp I want for the desktop, this is a really good price/performance piece of kit and definitely adds something to the iDSD. The XBass and 3D perform differently to my ears compared to the iDSD (more subtle) and having an extra step in XBass is nice to have for some tracks.

I am sure the iDSD is pretty good too

Much like 227qed I found both the Xbass and 3D enhancement a major boon here. BTW the - mark is 'Off" not subtract at least on the original Ican it was.
I also owned the LC alongside, and I agree it had a major mid boost, but it's deep bass was nothing of a sort as full, especially compared to the Ican, and if that's a closest thing to tube amps, I'll gladly stay away from them.

Not the closest. But it is indicative of what a tube amp has, like added harmonics, warmth, lushness, etc. It has more tube than the iCAN. And you're right. There are dots. One dot is subtract, three dots add and a dash is off

I thought the Ican was much more smoother or "lush" although these subjective stamps are vary to person to person, and it might not mean anything to some. In any case I would recommend the Ican over the LC any day regardless of price and for the current price difference it's a no brainer IMO YMMV
Oh BTW thanks for the review!