1. Rest assured that this unit, which "died in a few days", would have been a no-brainer of a return whether you bought direct from store.hiby.com or Amazon.
2. Do you see any issue with basing usage and sound impressions on a unit that died in a few days, while it was "alive"? I do. Certainly your impressions are not in line with impressions I received from people whose units did not die in a few days. The only problem reported here that I see reflected in other people's reports is the battery not charging to 100%. That is an accounting problem with the comloub counter that has since been rectified in a firmware update. The 29 hour uptime being it playing local music files with screen off (you'd find it reported similarly from the likes of Sony), the onboard amp being a power-efficient one built into the CS43131 HiFi SoC, the screen-on time would indeed be much less.

In any case, we're sorry you had received a defective unit; I presume you have received a full refund by now. If not, let me know.

But in summary, I do not see the point in anyone writing a review based on a defective unit, unless it can be shown that defective units are the norm here.

Best regards,
Joseph Yeung
HiBy Music

Also, 2000mAh is nothing next to most smartphones running a Snapdragon 665, so apart from the screen-on time being less, it would also be more dependent on activity than other devices, and has nothing to do with the battery being subpar (2000mAh is 2000mAh). But it is also true that other DAPs can hardly break the 10 hour mark, even with screen off and playing music offline only, while the M300 may reach 29 hours in that scenario, because of different amp circuits.

Hello, I have been using this player for several weeks now and at the moment it works perfectly. For the price of the device and all the functions it has, it couldn't be better. For me the battery is more than enough and I use Bluetooth and Wifi at the same time, the sound quality is a normal sound with a great emphasis on the lower frequencies designed for generation Z who only like bass. I picked up this device because at the moment there is no smaller Android on the market and to carry it around constantly it is the best option. After having tested both its 3.5mm output and Bluetooth, I have to say that this player is worth it if you are going to use it with Bluetooth, for this it is perfect if, on the other hand, you are going to use the 3.5mm output, I would better look at another thing because I didn't like its sound at all.

@Joe Bloggs I appreciate your comment, and do not take it lightly. I do see this review being fit, even on a dead unit. I am not saying bad things about the unit, merely that such a manufactured run that it currently is in needs further quality control. I enjoyed the unit, and cost effectiveness it is offered at. However, I think more users have experienced problems that are critical failures rather than cherries and roses like everyone claims. I loved the usage I got out of it, sound, and many features it offered. I am writing a review strictly on my thoughts, and how I feel. Not with intent of bringing down a product, company, or brand. I'd be willing to give it a shot another day in the future, just not under the expense of potentially losing money. When I invest in equipment, I am under the assumption it will be money well spent and last.

@Joe Bloggs I have returned this item to Amazon, with the consultation of your companies support at the helm. They were very nice, but I cannot simply see myself buying another unit given to try to turn this negative to positive. I'm a firm believer in reliability, and this product does not seem to be the best in that department. I was skeptical on Amazon reviews, when one user wrote he returned multiple in a row. My opinion is unbiased, and something I am willing to discuss. No ill will my friend.

@jorgeju115 Well said, I bought this device for the usage of the 3.5mm output. I wasn't impressed much, and had planned to get use out of the Bluetooth functionality... but quickly reconsidered once I seen the battery issues/life. Size is also a big plus.

@jase2k I can see the multiple returns review by McKeever on Amazon but what he is referencing are issues with the software not performing as he wants. Given the nature of his problems 100 replacements would not have changed a thing, he should either have returned the unit for good or simply waited for firmware updates (which are coming thick and fast in response to users' comments). His problems still stand apart from the hardware failure in your case.

I appreciate that you are writing about quality control issue such that you received a dead unit, but then I don't see how that translates to "Do. Not. Purchase. (You've been warned)"? Do you have evidence that the majority of users will receive a dead unit like you did? Or that that would result in anything worse than a return for a full refund, wherever you buy it from?

Regarding the 3.5mm output, I am not usually a believer of having to pair high end megabuck sources with earphones to get the best out of them, but the comment that the earphones sounded gritty does sound like your RS1 with under 100dB/mW efficiency are being underdriven, at whatever volume you were listening at. Again, I have stuck plenty of earphones, even full sized ones, into various small device SE outputs and been pleased with the results, but that is limited to high efficiency sets, (power efficiency, not voltage efficiency) preferably of medium or even high impedance, reason being given here: https://www.head-fi.org/threads/the-discovery-thread.586909/page-6425#post-17996720

in a nutshell: high voltage swing requirement is ok with any source as long as you don't max out the volume knob, high current requirement is truly challenging at any volume setting. People often disapprove of using almost any portable source with almost any headphones, again, I don't usually side with such norms, but if pairing one of the smallest sources out here now with these higher current draw full size 'phones, there just might be something to it.

The other possibility is with DSP / EQs in player software being driven into digital clipping, but I'm not going to speculate that you used any such thing without suggestion of such on your end.