Fosi Audio DS2 USB C to AUX Headphone Amp DAC Dongle 3.5mm Jack Audio Portable Amplifier Dual Output DSD256 4.4mm Balanced High Resolution CS43131 for iPhone 15 Pro Max Plus iPad Android Phone

---Update--- Fosi has been communicating with me and been very helpful to solve this issue. They are so nice to deal with and glad to have your business and I'm glad to give them mine. They must have the smartest tech support too to be able get through to me the things they have been able to when I've asked them for help. And they have a lot of very great electronics that most of us can't get enough of! :) ---Original--- I bought a new item and label on box says new too but the round tape that was trying to seal it closed(see picture) was barely left with any adhesive left in it and full of lint as if it had already been opened and tried to be resealed and returned for resale or to be refurbished so I opened it and while opening it it made so much noise from everything loose inside. But I did not buy a used or refurbished item that this appears to be, nothing inside was in place. I figured as long as I had it I might as well give it a listen, so I did. I have many Sabre DAC chip equipped pieces whether in phones or dedicated DAC/amps and most recently a dongle from HiBy, an FC4 and I thought this would be a nice change getting away from ESS chips and give Cirrus chips a go, I couldn't be more surprised when A/B testing them(from memory((from side by side))) that are so very similar. I don't possess the words to describe how minimal the differences there are between the 2 chips are when used in these 2 applications, it is really amazing. I was expecting a lighter, relaxed, atmospheric, type of performance from the DS2 but it is every bit as analytical as the HiBy and Sabre chips. Still worth having both to me by the way, due to power gains had in the Fosi DS2. You wouldn't guess there were gains in power made in by the DS2 until it's about half way turned up then it's just thick and loud sound. Beautiful, thick and loud. I don't quite know how adjustability is done on the DS2, I think instructions suggest downloading the HiBy music player app which in all fairness has very many types of adjustments DACs it's just that the player itself seems to be causing a lit of problems for me, so I'd use it for adjustments and go back to your normal player for your music and and streamer once done with adjustments. That's just what I've found to be best for adjustability on HiBy and may not be true of Fosi. Oh also, the HiBy player tries to load twice when I plug in my USB dongle, so I uninstall the player until I want adjustments. Crazy but true. Lol Anyway, I can't say enough good things about this Fosi DS2, I wish it shipped looking like it was actually new and left me not questioning, but it sure seems like a high performance, very high quality, very great value. Performing equal to many above it's weight class and caliber. I'm so surprised it sounds nearly identical to the Sabre DAC chips that I'm used to, I've read so much about Cirrus and thought I knew what I was getting into. I pleased with the sound and will keep the DS2 as part of my setup due it's power alone and clean power at that. And Fosi is now a part of my future equipment too! This really impressed me. I hope I've been helpful, Thank you.

The Fosi Audio DS2 pairs perfectly with my CrinEar Daybreak Triplicate-Hybrid in-ear headphones. Audio is clear, detailed, and has plenty of power to drive them without distortion. I’ve tested it on Windows, macOS, iPhone, and iPad, and it works flawlessly on all of them. It’s compact, well built, and easy to take anywhere. For the price, the sound quality and performance are hard to beat. If you’re looking for a solid DAC/amp for quality IEMs, this one delivers exactly what you need.

I've used this little Fosi DAC/Amp at the gym daily 5-6 days a week for 2 hours a day for weeks. Below is a quick pro/con summary and the associated gear I used with the Fosi. I then delve into my impressions of this slick little device plus a comparison with the higher priced and highly adjustable Qudelix 5K DAC/Amp with an internal rechargeable battery. What I like about the Fosi: pocket friendly well built intuitive simple and inexpensive solid upgrade for properly fitted IEM use in noisy environments. What I don't like (and why I knocked off one star): the Fosi is a power hog on a new iPhone cheesy USB C to USB C cable needs immediate replacement The IEM gear I used with the Fosi (I keep my IEM's in Pelican cases for protection, they are NOT stock): Ziigaat Odyssey IEM Moondrop Dusk IEM (Crinacle) 7HZ Timeless IEM iPhone 16 pro - new as of 4/25 Tidal streaming app for iPhone Thunderbolt 5 Cable high Speed 80Gbps Data Transfer,16K/8K/4K type c to type c The little Fosi adds depth, bass, timbre and soundstage to all 3 of the aforementioned IEM's which are all considered best in class for the price on the Hangout Audio website curated by the wizard of IEM's "Crin" or "Crinacle" aka Corin Kohn. I used the Fosi and interchanged my various IEM's at the gym every day which may appear initially to some as a loud and semi-absurd place to review IEM's and small DAC/Amp. In reality, it's ideal because noisy gym replicates the worst of the real world and puts IEM's, the ear bud tip choice and a DAC/Amp to a strong acid test. The Fosi passes for its low price point, dynamics and simple connections which are USB C to USB C in my case, and I bought a top-quality aftermarket USB C to USB C cable because the included cable is chintzy. One key here about ear bud tips - cheap, ill-fitting ear bud tips can make even a top rate DAC/Amp sound bass free, with thin mid-range and a tinny high end so get good quality proper fitting tips before you blame the Fosi or other DAC/Amp for garbage sound. Be aware of two simple facts about the Fosi. Fact one is that it uses source battery power (iPhone battery in my case) and it has volume buttons +/- that act independently of the iPhone volume buttons. The Fosi power drain is significant. 2 hours of Fosi use with my nearly new iPhone 16 pro drains the battery from 100% to about 84%. When using just an IEM for 2 hours, I get a 4% power loss from running Tidal and negligible power loss when using a Qudelix 5K DAC/Amp that has a rechargeable onboard battery. The Fosi onboard volume buttons sound like a silly thing to talk about but you can have your iPhone volume wide open and the Fosi volume set very low and get terrible Fosi performance. Adjust both the Fosi and source volume appropriately. I show a couple of photos of the Fosi next the slightly larger Qudelix 5K DAC/Amp. The Qudelix is about $100 on sale on Amazon but it's next level for total audio control because it includes a 10 and 20 step equalizer, a terrific app and a mind-boggling amount of audio adjustability for any headphone or IEM. The Qudelix allows for wildly expansive audio tweaking but it's complex and the Fosi is simple. If you want plug and play, get the Fosi, if you want total mastery of your head related audio and are highly audio tech savvy, buy the Qudelix 5K. I hope this data helps you make the best in this category for your own needs.

Wow, really great. doesnt add coloration and has a little umph. I have this paired with Shure 840a and it is a great combination. Quality is very high, performance is high, cost is kept in check. Highly recommend this combo if you want something dip your toes into the higher end of audio but do not know if it is worth it or not. This will give you a great taste - for reference I mean natural tonality. I also use this on my IEM, which is a better fit for this dongle and it sounds great. The balanced output does actually add a little quality and umph if you do critical listening and comparing but it is not night and day by any means.

La verdad es que si hay una gran diferencia al usar este aparato con unos buenos audífonos, ojo hay que usar fuentes de buena calidad si quieres sacar el mejor provecho yo uso Apple Music y hay canciones que vienen en Hi-Fi y se oyen de maravilla, como por ejemplo el álbum de Pink Floyd The Wall

This Cirrus CS43131 based DAC/ Amp "dongle" combo is a little wonder. I decided to give it a try after reading the positive review on Audio Science Review. I was on the lookout to replace my aging FiiO Alpen portable DAC and this appeared to be the perfect replacement. It is has a diminutive size and no rechargeable battery which makes it light and eminently portable. It does take power from the unit it is hooked on but the drain is not all that bad especially if used with efficient headphones, especially IEMs. External volume controls and an additional (unheard at this price) balanced headphone out add incredible value to an already fully featured unit. For actual measurements and all that jazz you can refer to the extensive set performed by Audio Science Review. Long story short for the TL:DR people, the measured performance is exceptional, rivaling good desktop/ dedicated DACs/ Amps, featuring low noise/ distortion/ jitter, high linearity/ dynamic range, great filtering and very decent distortion free output power (43mW into 300 Ohm load and 172mW into 33 Ohm load). I tested this unit hooked up to my iPhone 13 Mini, iPad Air 6 (M2) and to my PC Workstation, running iTunes/ Apple Music/ Foobar2000/ JRiver MC33. The headphones tested with it were: HiFiMan HE400i and RE-400, PSB M4U, Beyer DT240 Pro, Final E-4000, Moondrop CHU II. I am very familiar with these headphones, I used some of them for years hooked up to some pretty decent pieces of gear in my possession, such as Accuphase and NAD preamps, Arcam, Denon, Rotel, Topping or SMSL DACs and my Nak, Oracle analog front ends. Now, with the name dropping aside, I will touch briefly onto the sound of this unit. This diminutive DAC/Amp had no problem driving any of the above mentioned headphones, including the HE400i, whose planar design is generally posing a challenge to portable gear. The Fosi DS2 handled everything with poise and grace, without any hint of distortion or clipping. As for the "sound" itself... well it sounds like nothing, as it should. The Fosi DS2 has no "character" of its own so does neither add nor subtract anything from the signal it is being fed. Similarly with any true high resolution/ high fidelity playback unit, the music comes thru clear and uncoloured, faithfully representing the recording or the material being played. I like using a FLAC version of the Triangle CD Demo, which has pretty much everything you want in terms of sound, from closed miked voices and instruments to large orchestral ensembles, from intimate jazz tunes to big dynamic swinging symphonic pieces or glass shattering, garage door banging sounds. This recording, along Pink Floyd's DSOTM and Mike Oldfield's Tubular Bells II are the ones I'm typically relying upon in this kind of subjective testing. There isn't a hint of harshness, sibilance, bloom or any of those things professional gear reviewers sometimes use to describe what they hear. The Fosi DS2 would leave these reviewers with almost nothing to say really, its musical performance reflects closely the unit’s exemplary, almost textbook perfect bench performance. 100% recommended, this diminutive DAC/ Amp unit punches way above its weight. It matches or it exceeds performance at almost any price level.

アップルのヘッドフォンジャックアダプタを最初に購入しましたが、スマホ側の音量をMAXにしても音が小さかったので、こちらを購入しました。結果、満足できる音量を設定できるようになり、買って本当に良かったです。 ​​​​​​​

This is my first DAC. I was not sure what to expect and what improvement it will make to audio. It does improve the sound significantly. Got subscription to Tidal. Now enjoying music on my JBL headphones.

I have been using this since six months & really enjoying it. Mostly I use this to listen Apple music as it has hi res audio support with lossless audio content. With fossi ds2 dac the experience is next level