@Brooko Of course, they are in different categories. But I thought it would be interesting info to know how they square up when it comes to SQ, especially since good, budget equipment is thought to be something of a rarity Enjoy! I had to find an excuse to sell mine, only because I have the m9XX. If I didn't, I would take the Slim and K7XX and run.

Oh - nice.  Are you going to review the Grace M9xx?

@Brooko I have, that's my only review so far I'm truly happy with, IMO. The only thing I would add is impressions with the HD 600, since that's one major headphone I didn't have time to really listen too with the combo.
Perhaps you could ask Will Bright for one, I'm sure with your reviewer background he would at least have to think about it. A decent DAC/amp for both IEM's and open-backs, although I don't think the X1S's SQ is as far behind as the price would indicate. Still, it has many features the X1S does not (sort of like the X5ii and E17K, actually), so it's definitely worth a shot. You have a lot to talk to Will about, if you want to get both, lol.

Your reviews are refreshingly honest, informative yet concise, and strike a remarkable balance between objectivity and subjectivity. Keep up the great work Brooko!

I used to have the old Alpen (the one with the optical digital input).
The built in amp actually didn't do too bad a job of driving my AKG Q701 'phones.
The S17 with with an E09K actually did a very nice job of driving a pair of 600 Ohm Beyer DT880 I also used to own. But I found the E17 was not a neutral enough DAC for my Stax SRS-2170 system so I sold the E17 + E09K.
Nice review, BTW!

@justjag - thanks - this sort of feedback makes it all worthwhile
 
@Chris J - appreciate the insight.  I think you'd like the new E17K sig, and especially with Fiio's K5 (review coming soon).  Very much on the more neutral side of things.

I actually started out with a E17 back in the day, such a wonderful step in toe audiophile land. This review brings back that emotion and experience again. Thank you Brooko!
 
The K5 has me intrigued too! 
 
Viva La Fiio!

K5 is actually really good with it - as a charger and a dock. I just wish it had variable out via rear RCA's - then it would be perfect for desktop use (with active monitors).

@Silverylos 
@Andi Lam
 
I tried the E17K (paired with the X3ii) with the K701 tonight, and used it side by side with my iDSD for comparison.  I was actually really surprised how good the E17K + K701 pairing was, but the reality is that the iDSD was better. A more dynamic overall signature. more sense of space, and greater overall definition. The E17K was a bit brighter, and the bass wasn't quite as well defined.  Saying that though, the E17K didn't feel as if it was underperforming with the K701, so on that basis, I'd give it the thumbs up, and to darken the signature a bit - just apply a little +2 or +4 bass.

Has anyone compared the E17k to the Oppo HA-2? Specifially, for use and a DAC+Amp on a Android Smartphone? 

Sorry - I haven't heard the Oppo.  Ican confirn the E17K will work with my iPhone 5S and appropriate cable - as dac and amp.  Sound mighty fine too!

Amazing review, thanks!

Thanks - I appreciate the feedback.

Nice review Paul! Let me tell please where is the "secret" - comparing X3IIs and E17Ks specs - almost same.:200mW on 32 Ohms, output 7.2 Vp-p, aside from sound quality? Where is the more power, another  power supply? Just curious. I'lld like to drive HD600,  as yourself in this review. (Ordered the E17K. , few days ago    )

As far as direct power goes - the X3ii internal amp is almost as powerful (E17K has slightly higher voltage output - but it's negligible).  The secret is in the additional gain, hardware EQ (which is excellent), and the ability to bypass the X3ii amp.  By bypassing the amp you extend the battery beyond the X3ii's 10-11 hours out to around 15 hours or so.

Thanks! Yep, I'll probably use the digital out from X3II. Can't wait to try!

Interesting review! Thx Paul!

Hi all, not quite sure if this is the right place to shoot this (probably stupid) question... still here it comes: I see that Fiio E17K Alpen 2 has a Frequency Response of 20 to 20,000 Hz. If I buy it for Seinnheiser HD 569 that has a 10- 28,000 Hz, how exactly will be the frequency gap influence the sound? Thank you,

Generally accepted human audible range is from 20 Hz to 20 kHz.  FiiO always understates their specs - you can bet that the E17K would be able to produce higher frequencies under a scope - but there really is no point.
 
Depending on average age, human audibility of the frequency range will vary.  i'm close to 50, have tinnitus, and my audible frequency range is from about 22 Hz to around 14-15 kHz.
 
I'm betting that unless you're super human, your audibility will top out under 20 kHz.  So the extra that is discussed in the specs really means nothing as far as audibility goes.  EG - I have the HD800S on my head at the moment.  They have a published frequency range of 4 Hz - 51 kHz.  Even from the E17K + K5, they sound pretty darn good

Great Review thanks.
 
I already had the X3 II and ordered the E17K today based on this and wanting to have the bass and treble option at hand.
 
So I assume set the EQ on the X3 II to flat and gain to low and adjust on the E17K side, what did you find to be the best volume output from the X3 II to the E17K for a start ?