M15i Headphone Amplifier [MFi Certified] Portable USB DAC Amps with 4.4mm and 3.5mm Dual Outputs Supports PCM 768kHz/DSD512 High Resolution Lossless for Smartphones/PC/Laptops

My current headphone setup is about $5,500 without including headphones. A Holo Bliss KTE, a Holo Cyan 2, and a Holo Red Streamer. As far as sound quality goes, this tiny $250 thing is punching closer than it should to my big setup. It doesn't have as much power obviously, and doesn't sound as big, but it's still very impressive. I have only used 4.4 balanced with this dongle because using 3.5 dramatically reduces output. So, using 4.4 balanced, I've tried Hifiman HE1000SE, Sennheiser HD600, and ZMF Bokeh. It's not ideal for high impedance like HD600 @ 300 ohm. But it is acceptable performance for 300 ohms and would probably satisfy most people. It drives the HE1000SE and Bokeh very well. There were moments where I just shook my head and felt a bit silly, because sure my $5,500 setup sounds twice as good as this $250 dongle. But at 22 times the price. That should impress even the most skeptical listeners. Also, it's portable! This thing is a clear winner and an incredible value.

I loved this dongle amp/dac. It has a very clean and neutral presentation and I've driven a 64 Audio U4s IEM, a closed-back Focal Stellia, and an open-back Focal Utopia with this little thing. No problem with any of these and it's particularly good from it's balanced 4.4mm output.I'd also like to note that Questyle's usb-c to Lightning cable (unfortunately it needs to be purchased seperately) is one of only two brands of "short" dongle cables that I have not had issue with (even the high-end cable can exhibit too much wiggle in the Lightning port, causing the dac/amp to disconnect).However, I did have a problem. The M15i died on the 6th day. It simply would not connect or power on. Note that it was not due to a bad cable; I tried several others and none worked.That said, I love this dac/amp so much that rather than return for a refund, I requested a replacement. I'm hoping I will be able to return with a positive update, but for now I have to give this a low rating.UPDATE:The M15i mysteriously came back to life. Not sure if it suffered thermal shutdown (note that the case was cool when it died the previous day). Currently sounds great, but I'm still going to return this one when the replacement arrives as I fear this may happen again. Do note that I'm still going for a replacement rather than a refund because I love it that much.2nd UPDATE:Replacement M15i arrived and it has been stable. Customer support was good, although replacement took longer than expected to arrive. I guess replacements do not qualify for Prime shipping; I should have returned for a refund and then bought a new one (that would still qualify for 2-day Prime shipping).Despite having run into a shutdown issue on the first unit, this is still currently my favorite dongle dac/amp. It gives me the mobility I want while using some high-end IEMs.

This dongle is great for my Hifiman Ananda headphones. Plenty of power. The DAC section sounds solid while not amaizing. For the price (got it for 180 USD) and size the performance is satisfactory. Would recommend.

This thing sounds fantastic. I am using it with $900 Sure SE846 headphones. I haven't listened to any other dongle DACs so I don't have much for comparison, but compared to other audio equipment I've listened to over the years, this thing is precise and musical. It has a lively sound, playing FLACs from my iPhone via Doppler app. Just sitting and listening to music, doing nothing else, is very enjoyable now.The device seems to work best with Apple devices. I tried using it with my Windows desktop PC, but the sound was not nearly as good. I have no idea why. I won't bore you with a subjective description of the sound, just know it may be hit or miss with Windows. I haven't tried it with Linux yet. Fortunately I only need it for use with my Macbook Air and iPhone, but more compatibility is always good.The only improvement I could suggest to the manufacturer would be a small volume dial. From what I have heard while cruising the internet, software volume control causes a reduction of the sound quality. I have no idea if this is true, but supposing it is, it could be avoided with a volume dial. The sound and detail on this device is great so it may be beyond my ability to hear.If you're considering this device, just get it. I almost got a DAP instead of this DAC, but I'm glad I got this. While it does limit the compactness of the phone, I think it is better than fiddling with a crappy version of Android on one of the many DAPs out there. Until a new version of the iPod is released, I think this is the way to go. You probably have better battery on your phone with this plugged in than you would with many of the DAPs running Android anyway. I'm just a guy yapping, make your own choices. But know that this thing definitely has brought me happiness and I hope you enjoy it, too.

Good while it lasted. Only used for a few times at home and the USB-C port became loose and now no longer connects. They claim a one year warranty, but there is no way to get in contact with them to file a claim. Stay away.

It worked well for a couple months but now it won’t turn on with my iPhone and does not work entirely for the phone. The audio quality was good but paying this price for something that won’t work after a couple months is not very good. This product is way too expensive for use problems. It was used very lightly and not damaged so there is no reason it does not work anymore. I am unable to reach out to questyle about the warranty replacement as they will not respond and there is no way to contact through Amazon it seems. I cannot sell it as I am unable to test if it even works anymore. Overall 2 stars for good audio quality but not any higher due to the quality control issues and lack of customer support. Not recommend.