Over the last few days I've been comparing the diminutive DX170 to the behemoth that is the DX320 (will be referred to as the 170 and 320, respectively, from hereon in). This isn't going to be a drawn-out, overly verbose review with flowery prose, but more an abridged summary. Let us commence:
The 320 is a sizeable fellow. With dimensions that are more or less similar to my Oppo Find X5 Pro 5G from face on, but about twice the depth. After holding my 170, going back to my phone has always made me more aware of its size, and now the same happens with my phone after handling the 320! However, he manages to remain svelte in the hand, despite being considerably more portly than 170, thanks to iBasso's thoughtfully applied curvature in all the right places (think Christina Hendricks-esque). It is still - just about - pocketable, but you'll notice its presence, whereas the 170 is so light of heft and slim of dimensions that you could probably have it in a shirt pocket without much drama. There is no doubt about it, the 170 is so much more convenient for moving about with in your everyday life. The 320 is on the very cusp of being too big to be considered anything other than transportabe, but you could still head out with it in a jeans pocket (depending on your jeans, if you're a skinny jeans kinda guy, don't bother... or shove it in your pants for some extra padding).
I've not seen any reviews mention the slight flare applied to the right-hand edge of the 320 which improves ergonomics while one-handedly wielding such a device, but it is an appreciated aspect of usability. It can't be more than a few degrees but makes it that much easier to interact with the volume wheel and playback buttons. This is what I like about iBasso, they almost remind me of the Meze of the DAP world, in the tiny details that they really didn't have to go the extra length to implement, but did anyway, because they care. You can see they share the same lineage from their design-language (size apart), with a few small changes. The 170's buttons are circular to the 320's rounded oblongs, and the 320 also has a thumb-sized depression in the middle of the power button. I don't know if this necessarily adds better ergonomics or aids interaction in meaningful way, but it sure does feel nice to have it cradle your thumb for reason's I can't quantify. Try it out, you'll love it. The 320 also mimics modern smartphones closer with rounded corners at the extremities of the screen, where the 170, while still not A&K angular, is more traditionally rectangular.
The one thing I think they actually improved on the 170 over its older and more expensive siblings is the discreet, curved bevelling where the frame meets the volume wheel. This acts to absorb it into the device structure and protect it from accidental nudges, or from being subjected to potentially increased pressure whilst being in a pocket, while on the 320 (and 240) it just sort of protrudes, like a shiny, machined fungi. Again, iBasso didn't have to improve upon a design aspect with their lowest priced model, but they did. It certainly doesn't feel like the 170 was made as an afterthought for those who couldn't afford models up the food chain, but really as a stand alone device in its own right to fill another particular niche that also happens to be the most affordable. The screen on the 170 is also arguably better than the one on the 320 in everything other than sheer size. The 320 still has an excellent screen, but the 170 is brighter and more vivid, without appearing overly saturated. I also prefer that the volume adjustment on the 170 goes from 1 (or 0? I've never tried) to 99, over the maximum 63 on the 320 if for no other reason than 63 is so seemingly arbitrary it's just weird. I'm sure there's a reason, but it took a while to get used to and remember that when I was on volume 30 on the 320, I wasn't just under a third as I would be on the 170, but closer to halfway of available adjustment.
Spec wise, similar to size, the 320 eats the 170. It's not even close, nor should you have expected it to be. The 320 is easily as fast as any modern day smartphone in most applications that you'd be using it for. Web browsing across multiple tabs while playing music in the background, and swapping between apps present no hurdle to the 320. It is snappy, fluid and every bit a flagship in general operation. I've not tried gaming on it, but I'm sure it could handle those with more conservative minimum requirements, but please, don't buy this to play games on. The 170 on the other hand, is, well, acceptable. Once you've disabled animations and uninstalled APKpure, that is, and even then, don't be expecting to run multiple apps and switch between them with the deftness or absent mindedness you would on while using your phone. It was designed to do one thing; play music. And that it does. Let us harness this segue to, at last, move on to sound.
So, the 320 obliterates the 170 on performance, and therefore you most probably expect it follow suit on matters more audible given the price delta. Except, it doesn't. I'm going to go ahead and say it right now, they are closer than you would imagine, and certainly not night/day different. Before elaborating any further I'll make it known that I used my Fostex TH900 and a Meze Liric (both through balanced outputs on both devices), and my Shure SE846 (single ended) to make my impressions. Sure, none may be considered summit-fi, but neither are they lacking in transducer quality to be able for me to come to a pretty decent conclusion.
This comparison will possibly be the shortest between the devices simply because there are less pronounced differences to cover. The 320 with its ROHM chips is more linear, more neutral, and ergo more 'reference' sounding. The 170 does have a smidge more warmth down low, and adds some upper mid prominence. Bass could possibly be a hair more impactful through the 170, but its close. The 320 does improve layering and micro-detail rendering, and perhaps the holography of the soundstage, but I found the 170 to be at least equal in width. The 320 does sound ever so slightly more organic, more realistic, for reasons I can't properly articulate, perhaps as a result of the whole effect of the marginal technical increases, but again, we're talking in realms of minutiae more than mind-blowing and obvious. I think the biggest take away for me was that I expected to be let down going back to my 170 and I absolutely didn't. I think iBasso made the right call nuking it on hardware, because this area is the biggest draw for improvement. The 170 has a surprising amount of power on tap. I had the Liric between 40-45 in high gain on the 170, and between 25-32 on the 320 - but remember, the 320's volume tops out at 63 against 99 in the 170. For higher impedance or harder to drive headphones then sure the 320 will pull away as it gets into the upper registers of its volume, but with the gear I was using power and drivability never showed up any inadequacies on the 170.
Given I had the cash available would I buy the 320? Why yes, yes I would. However, it would be less about the improvement in sound quality and more for those gains in hardware. In fact, there is a place for both in a collection. They serve different needs, and my experience with the 320 was a win-win for iBasso because not only did it serve as the perfect duel to highlight the value the 170 offers from a convenience and sound-quality perspective, but in addition, its 320, despite being far from crushing the 170, takes everything I love about the 170 and puts it in a similarly beautiful device that expands on its usability. I could, and hopefully will, own both one day.
(Yes, this is the abridged version).