Imo yes but the SE425 isn't bad either in this price range as it also has got a neutral-ish sound signature (actually the SE425 is more neutral than the SD2) but is more precise, has got a  way more solid bass and has got a slightly higher resolution and does not have problems with faster music.
Highs roll off earlier though and the soundstage (if you could even call it so) is pretty narrow but has got a nice 3-dimensional presentation. With the SD2, I can always hear the holographic soundstage whereas I have to concentrate hard to get it with the SE425.
The SD2 sounds more authentic overall whereas the Shure is more precise but also has got some clinical touch to it.
 
Personally, I like the SE425 more for regular otg and prefer the SD2 for stationary use, indoor sports, gaming and movies.
 
The only real disadvantage of the SD2 is that faster music doesn't seem to please it but I really love it for its awesome imaging and authenticity.

HiFiChris, how do you compare SD2 to your Ultimate Ears In-Ear Reference Monitor? I'm aiming for that as my last stop, hehe..

The UERM are very close to being neutral. Some might say it's boring. If you want to get an impression of the UERMs' tonal balance, you could try the Ety ER-4S which come very close to the UERM despite having too much upper mids making voices sound high-pitched (it may be tip-depentant).
 
As I said, the UERM are much more neutral. Switching from the SD2 to the  above 10kHz where the SD2 has got almost nothing.
In general, the UERM also have got more tremple than the SD2 (which has UERM, you feel like there is no bass at first.
The UERMs' mids are without any coloration (the SD2's lower mids are little emphasized).
High extension is much better with the UERM - they have got a nice sparkelea moderately recessed treble).
 
The UERM are pretty unforgiving and reveals bad recordings whereas the SD2 is still tolerable.
 
In terms of imaging, the UERM are more precise and can display space between instruments better than the SD2.
On the UERM, stage is only there when it is on the record and then it is phenomenal. I remember having heard a classical piece long time ago where i could literally hear the audience behing me which was somewhat scars. The SD2 benefits from recordings that already have got a good imaging but also lets recordings that don't really have got a stage sound 3-dimensional.
I would say whilst the SD2 seems to have the same stage dimensions all the time, the UERM really reproduce what's on the record.
 
Both IEMs sound very authentic. Literally: The UERM was the first IEM that really got me feeling like I was live on stage and made me cry. The SD2 was the second that came close to the UERMs' authenticity.
 
One more thing: the UERM require a source with an output resistance of less than 1 Ohm to sound tonally correct whilst everything below 2 Ohms does it for the SD2.

xaddictionx said:

How does the SD2 compare to either the se846 or ASG2?

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Go connectit compare

hifichris said:

  The UERM are very close to being neutral. Some might say it's boring. If you want to get an impression of the UERMs' tonal balance, you could try the Ety ER-4S which come very close to the UERM despite having too much upper mids making voices sound high-pitched (it may be tip-depentant).
 
As I said, the UERM are much more neutral. Switching from the SD2 to the  above 10kHz where the SD2 has got almost nothing.
In general, the UERM also have got more tremple than the SD2 (which has UERM, you feel like there is no bass at first.
The UERMs' mids are without any coloration (the SD2's lower mids are little emphasized).
High extension is much better with the UERM - they have got a nice sparkelea moderately recessed treble).
 
The UERM are pretty unforgiving and reveals bad recordings whereas the SD2 is still tolerable.
 
In terms of imaging, the UERM are more precise and can display space between instruments better than the SD2.
On the UERM, stage is only there when it is on the record and then it is phenomenal. I remember having heard a classical piece long time ago where i could literally hear the audience behing me which was somewhat scars. The SD2 benefits from recordings that already have got a good imaging but also lets recordings that don't really have got a stage sound 3-dimensional.
I would say whilst the SD2 seems to have the same stage dimensions all the time, the UERM really reproduce what's on the record.
 
Both IEMs sound very authentic. Literally: The UERM was the first IEM that really got me feeling like I was live on stage and made me cry. The SD2 was the second that came close to the UERMs' authenticity.
 
One more thing: the UERM require a source with an output resistance of less than 1 Ohm to sound tonally correct whilst everything below 2 Ohms does it for the SD2.

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Wow..amazing explanation. Thank you very much. If you have to pick only one IEM from all of your collections, what would you pick? Oh with one DAP to accompany that IEM..

Headfonics have just posted a review of the sd4 for any people potentially looking at purchasing it...just a heads up

link? 

@HiFiChris: Thanks for all the comparisons! While you're at it, could you say a few words about the FA-4E XB and how these fit in?

atmaka said:

 

hifichris said:

  ...

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Wow..amazing explanation. Thank you very much. If you have to pick only one IEM from all of your collections, what would you pick? Oh with one DAP to accompany that IEM..

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I guess it would be the UERM and the DX90 because of its low output resistance. Too bad there is no other DAP at the moment that pleases all of my tastes, but the DX90 comes the closest.
 
 

headdict said:

@HiFiChris: Thanks for all the comparisons! While you're at it, could you say a few words about the FA-4E XB and how these fit in?

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I'm now refering to the "new" FA-4E XB with revised midrange. I have posted the tonal differences between the old and new model in the FA-4E XB/Rhapsody series thread. I haven't compared the FA side-by side with my other IEMs as its main application is almost only outside so my descriptions may be a little vague.
 
 
The FA has got a very high resolution that comes close to the UERM.
 
On the tonal side, the 4E XB has got a v-shaped frequency response with an evenly raising bass that reaches its climax in the sub-bass area. If I'm not mistaking, the rise in bass starts at lower frequencies than on the SE846.
The FA has got some kind T.F10-ish sound signature without any bump in the upper bass.
Highs are emphasized but never harsh or annoying due to the high resolution - the FA-3E XB's treble was sometimes slightly harsh.
The midrange is a little recessed but without any coloration.
Treble, mids and lows have got equal resolution.
 
Bass impact is fast, dry and clean and can handle speed very well.
 
Soundstage is more wide than narrow and has got some depth but is more 2- than 3-dimensional, it lacks some layers in deptht.
 
Instrument placement is precise.
 
Treble extension is good, though not as far as the UERMs' (but comes close).
 
I'd say it is a Triple.Fi 10 with better resolution, better soundstage (I found the T.F 10's soundstage somewhat elliptical and 2-dimensional), tonally correct mids (the T.F10's mids are rather on the bright side), without the annoying bump in the upper bass and without metallic treble despite emphasis.
 
 
I'd say:
 
Soundstage width:
 
SD2 > UERM > FA-4E XB > SE846 > SE425
 
Soundstage depth:
 
SD2 > UERM > SE846 > SE425 > FA-4E XB
 
Resolution:
 
UERM > SE846 > FA-4E XB > SE425 > SD2
 
Bass quality:
 
SE846 > UERM > FA-4E XB > SE425 > SD2
 
Bass quantity:
 
SE846 > FA-4E XB > SD2 > SE425 > UERM
 
Treble Extension:
 
UERM > FA-4E XB > [SE846 = SD2 = SE425] <- these are very close so I don't want to judge without direct comparison.

hifichris said:

   
I guess it would be the UERM and the DX90 because of its low output resistance. Too bad there is no other DAP at the moment that pleases all of my tastes, but the DX90 comes the closest.
 

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How about the AK products? AK100II, AK120II or AK240? I have AK100II and it's quite satisfying.. until just now I tried Lotoo PAW Gold with my SD2, listening to Susan Wong - Step Into My Dreams 24bit FLAC album. Much better vocal, separation, detail, clarity.. Oh god why did I have to try it.. I don't know how to describe it, but it was a really comforting sound signature. No fatigue whatsoever and it feels like I can listen to the DAP for hours..

I prefer devices that have an output impedance below 1 Ohm.
Even though not all of my IEMs react that much critical with impedances above 1 Ohm, I get a bad feeling though I know it would only affect a treble dip of 0,5dB above 8kHz.

@HiFiChris: Awesome service - almost jokeresque. Keep it up while I'm thinking of more questions to come up with.
 

hifichris said:

  I prefer devices that have an output impedance below 1 Ohm.
Even though not all of my IEMs react that much critical with impedances above 1 Ohm, I get a bad feeling though I know it would only affect a treble dip of 0,5dB above 8kHz.

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Hello there. You sir mentioned that SD-2 loses its precise flavour at fast tracks.. I do want further explanation because I purchased SD-2 from thomann 4 days ago and I solely want to listen hard rock&metal bands.. Btw dap is AK100 II.. 
 
 
Ps. I listened SD-3 before, but I never listened sd2. SD-3 was too how can I say it, curtained? like muffly and not clear. Bass was too intense that it ate other tones in my fav. bands anyway. (Iron Maiden, Megadeth, Graveyard, Rise Against, A7x, Opeth,Volbeat, Shinedown.. etc..) 

If you have listened to IEMs with BA trasducers that have got a good speed and handle fast tracks as precise as slow tracks, you propably know what I'm talking about.
The SD2 unfortunately, while having a precise 3-dimensional soundstage with rather slow tracks, starts losing precision the faster a recording is, especially in the lower areas: the IEMs sound strained, stage starts collapsing without precise locating of each instrument anymore, everything sounds washed-out. It has basically to to with the back-vented bass transducer which has got holes in it to couple with the IEM's shell's air to achieve more and emphasized bass. Back-venting isn't necessarily bad as other IEMs have already demonstrated - in case of the SD2, the back-venting doesn't work that well, imo. 
Maybe you don't perceive it that dramatic, I've already read of some people who listen to EDM, Metal and Hard Rock with the SD2 and like it.
Everybody perceives an IEM differently.
 
I haven't listened to the SD3 yet but it really seems to have a bloated bass covering the mids and highs.
Many who have listened to both of them clearly prefered the SD2 over the SD3.
 
 
I just looked at the impedance response graph of the SD2 and with the 3 Ohms of the AK100MKII you will experience some boost in the mids (especially the upper mids) and treble.

I've had the SD-4 with me now for a week and send them back next Monday. Will be putting out a review with full bells and whistles soon after. 
All in all they are v nice iems. Much prefer them to the SD-2.