I spent 40 minutes auditioning the HA-2 with an iPod Classic and an iPhone 5 as the sources and using my Ety in-ears.
Sadly, I concluded that the Oppo simply did not sufficiently improve the SQ over my iPhone to justify purchasing it.
This was disappointing as I'd gone intending to take it away with me.
There was perhaps a slightly wider soundstage taking an analogue signal from the Classic's headphone output but again, it didn't make enough of a difference.
Perhaps this was not totally surprising in light of Jim Rockwell's assessment of both Apple devices...

@UNOE That's why I've tried to include some basic measurement in my amp review. Number can be helpful sometime.
 
@SallyMae Of course improvement depends on both the source as well as the headphone used. If the source is good enough and the headphone isn't the demanding type, improvement can be small to none. But on a more personal note, I think Ety really doesn't need much amping. What it does benefit is less from power but more from the flavor of the amp, to compensate for Ety general coldness and slightly lack of texture in the bass to lower mid. That being said, I like my Ety with a slightly warmish amp, which won't take away Ety's transparency but still able to add back what is missing. In that sense, HA-2 is probably not something I'll recommend for an Ety.

Thank you. What amp/DAC combo would you recommend with Ety and Shure 425, given iPod Classic and iPhone source...?

I own neither iPod Classic nor iPhone (and generally pay very little attention to Apple's stuffs), so I can't really recommend one that will work for both. But if it is iPhone, iFi micro iDSD will be a pretty good choice over HA-2. One would argue Chord Hugo is also a great choice as well, but it is way too expensive and I won't say it is exactly transparent.

Nice condensed review! Thanks!
But where is the pictures?  Intentionally no pictures?

@earfonia What do you mean by 'no picture'? There are 10 pictures and 1 FR graph in the review. If you can't see them, I suspect it is your ISP. All pictures are hosted on photobucket btw.

Nice review, I own the HA-2 and I think you are spot on most of the things
To me it works wonders when connected as a DAC/AMP and is OK when connected only as an AMP. Other than that I'm really happy with this one!

@ClieOS Oh ya,... you're right, the pictures blocked by my company proxy. Now at home the pictures are shown.
I had a chance to borrow the HA-2 for a few days, and I agree with you, it is a 5 stars DAC+Amp, refined and transparent sounding.

Using it currently with my AK Jr (and occasionally my iphone 5s) and HD700 and it just rocks to be honest.

@ClieOS Brilliant review as always. I just hope you write more often

Could this amp/dac properly power the HD650?

@daivdmthekidd Don't own a HD650. But by spec, HA-2 should bet able to just drive HD650 to decent level at high gain. I doubt it will be the best of HD650 can sound though.

ClieOS do you feel the Oppo ha2 as an amp only has more to offer as far as sound quality then the Fiio e12a? I can get one for about 100$ more than a fiio e12a. 

@WhiskeyJacks E12A is pretty much the same as E12DIY with MUSES02, so in a way, it is just as good as HA-2 (as covered in the review). the difference is that my E12DIY is tuned for maximum transparency, which is how HA-2 sounds like as well, while E12A with MUSES02 is more of a mid point between transparency and musicality. So you can expect E12A to have a richer, more musical tonal, but not strongly color in any way. If it is purely used as amp, I am more inclined to pick E12A because I think it has a more versatile sound that can go well with different sound signature. Where HA-2's clean and transparent presentation might not go well with leaner sounding headphone. But truth being told, it is more of a choice on personal taste than technical merit. 

Thanks a ton ClieOS i just downloaded a flac player on my Samsung note 4 last night and was able to put my micro sd with my flacs in there. Man does the stock Dac and headphone sound lacking. LOL... I have never heard it though I have had the Phone for close to a year. I really would like to be able to use the oppo ha2 with it now that I have a flac player, but I have a feeling expenses will not let that happen. To be fair I am satisfied with the dac section with the DX90 for now. If it is going to break the bank I will be going with the Fiio E12a, and thanks for the responses ClieOS( apologies on not knowing you responded via post) I wonder how the PB2(the setup i have/had for it) does as far as transparency to the Fiio e12diy that you have.  

@WhiskeyJacks Can't comment on the PB2 as I haven't played with it before.

using a nexus 6p with the oppo ha-2 and it is draining my phone. Can someone list or direct my to where i can buy the below mentioned cable?
also a diagram might be helpful. thks. 
 
 you need to find a compatible cable in order to stop HA-2 from draining your smartphone battery. What you want is a bi-directional micro-to-micro USB OTG cable, not a one-way OTG cable (which is an older standard and rarer these days, but you can still find it)

@scherti23 all the information you seek can be found on the main HA-2 discussion thread in the portable amp forum, search for 'OTG cable'.

I am reading that the iPhone lighting port is going to be limited to 48 kHz and 18 bit for headphones.  When connected to an iPhone will it receive a 24/192? 

@Garrett Scheff Shouldn't it be 16bit / 48kHz? Can't really answer you as I don't own an iPhone. But if I am not mistaken, there are music apps that can bypass iPhone's limitation.