HIDIZS S9 Pro Plus Martha HiFi Balanced Dongle DAC & AMP, 768kHz/32Bit, DSD512 Portable Audio Decoding Amplifier for iPod Android PC with Windows/Mac OS/iOS/iPad OS System (Silver)

I mostly use bluetooth headphones on both my desktop PC and my phone these days, but still have plenty of traditional wired headphones and IEM's around, especially for more analytical listening, in and out of my studio. I have no idea who Martha is, but what I can confirm is that this DAC is tiny and has a USB-C interface, so it's easily versatile enough to just stick in when I need it. It has both a balanced and a standard 3.5mm port, so it's very versatile when it comes to headphone/cable support, too. Many DACs offer just one or the other, so having both, particularly at this price point, is a big win. It's all metal/aluminium, and looks way more premium than the price-point might otherwise suggest. It also has volume dials, too! Way too many portable DAC's seem to skip this now, and put all the work on the app instead. This doesn't even have an app, which is a good thing, IMO. I control the EQ from my own software, so I don't need any additional processing inside the unit itself. Just give me that clean sound stream, baby! I'd say it has a slightly warm sound profile. Very pleasant to listen to, with a wide, engrossing soundstage. Probably not something I'd use for mixing purposes in my studio, where a flatter sound is preferred, but it's definitely very enjoyable to actually listen to music with. Bass was deep, mids rich, and highs slightly laid back. No hiss or annoying noise-floor. A very clean, warm sound. For the price, this is a great buy. It has everything I need in a tiny package, and has the versatility to be used both inside my home, and outside. If all you want is a great sounding upgrade for the audio on your phone, then this is as good as it gets for the amount you'll be paying. Even as a desktop DAC, it's better than most of the competition in this price bracket.

The HIDIZS S9 Pro Plus Martha DAC/AMP is an excellent DAC and headphone amp for the money. It's a small device, and looks to be a high quality build, constructed from aviation-grade aluminium alloy and weighing just 17g! It offers a USB-C interface, and two outputs - 3.5mm and balanced 4.4mm. It has 138mW output at 32Ω for the 3.5mm single-ended connection and 180mW at 32Ω for the 4.4mm balanced output. The performance is good - it provides a much cleaner sound output than my computer sound card alone and sufficient power to drive the Sennheisers. An interesting fact - the reason they are called Martha, is in honor of the last surviving female Passenger Pigeon, the largest flocking bird species ever to have existed, that became extinct 109 years ago. Control options are limited to the two buttons on the device - these control volume and the filter options which are: Default - Vocals are slightly forward, and high frequencies are extended with reduced resonance. (GREEN) Linear phase fast roll-off - Enhanced analytical capabilities, delivering a clean and crisp sound (RED) Linear phase slow roll-off - Enriched harmonics, full low frequencies, and natural reverb. (BLUE) Mimimum phase fast roll-off - Balanced and moderate sound. (YELLOW) Minimum phase slow roll-off - Clean sound with a forward position. (PURPLE) Hybrid fast roll-off - Soft and smooth with enhanced detail. (WHITE) The selected filter is indicated by a coloured light. A shame that there isn't also smart phone support for configuration, but you can't have everything I guess! In summary, this is a feature rich, and performance headphone amp that delivers exceptional performance without breaking the bank.

I was attracted to this portable dac as it was using the same hi quality chip as the highly regarded Dragonfly Cobalt at a fraction of the cost. As is my usual practice, I looked at the Amazon reviews before ordering. All nine reviewers gave it a 5 star review, WOW, although ALL were "Amazon Vine customer review of free product" I received this new in good condition that hadn't been opened so it was supplied new. Connecting it to my iPad it didn't work. I then tried connecting to my expensive Android phone, this didn't work either, so sadly I returned it. VERY DISAPPOINTING PRODUCT. It's made me remember the saying "if something looks too good to be true, it probably is". I've been using 2 Cyrus soundkeys (purchased on Amazon in 2020) for many years it's a shame they are now discontinued. They were great sounding, very reliable and just plug & play.

I had the opportunity to try this 'Martha' DAC from HIDIZS; I'll be reviewing this as the average layman - because I am one! The closest to a similar device I have used in the past was an amplifier dongle that also provided virtual surround sound - a far cry from what is offer here. While I understand the terms used when discussing this DAC - I don't really have the ability to judge how they affect the performance. What I do have is a pair of ears though - so that is what I'll offer (audio quality comparisons - not my actual ears...). While I have tested this on Windows - most of my testing was done on a MacBook using Apple Music. The dongle is a fairly unassuming little metallic job. It comes with a fairly short USB-C to C cable plus an USB-C to A adaptor. The only controls are volume up and down (which in terms of a Mac control the system volume). There's a 3.5mm socket and a 4.4mm one. Being quite honest - I'd never even heard of that standard. Firing up Apple Music I dipped into the settings first to change to lossless formats. If you select "Hi-Res Lossless (ALAC up to 24-bit/192 kHz)" you get a warning that you will need an external DAC - which this Martha unit has you covered. Right - how to describe it. If you've tried various headphones in the past you probably know about different groups of qualities. Some have good middle but no bass, some have really good bass but the middle is 'muddy' etc. Then you get that occasional pair where everything clicks? The bass is punchy but not overwhelming, the middle is distinct and easy to pick out and the top end is clear and present - not thin. Now think of that as one blended audio image. What you get here is every instrument/element of the track feeling like it's lifted out of the 2D audio and positioned exactly where the engineer meant it to be. A "wide" sound is an understatement. I always use the same 2 tracks when testing audio equipment - Clearest Blue by Chvrches and One Day Remains by Alter Bridge. 2 reasons: one - I like them (which always helps!) and two - they both are quite heavily layered, always-on tracks. For the latter, the rhythm guitar stood out way more than it normally does and was quite distinct. With Clearest Blue - which is a mainly electronic track - I was picking up subtle echoes and reverb especially on the backing vocals that I'd never even noticed before! So yes - this works fantastically well. I really can't offer an opinion on value for money though. I'm the sort of person who has never spent more than £50 on headphones so stumping up £74.66 for "an enhancer" isn't something I would likely do - however I know there are audiophiles out there! In terms of sheer quality of output alone this has to be 5 stars.

HIDIZS S9 Pro Plus Martha HiFi Balanced Dongle DAC & AMP: Basically a more affordable way to improve your sound output without buying expensive equipment. It is smaller than you might think and it is lightweight, so it's unlikely to get in the way when plugged in. I think this is the sort of thing that won't be of interest to most unless you have specific audiophile needs. Like if you are looking for crispier sound from your audio output. You get 5 to 6 settings to adjust the sound to your requirements and you can tweak them to your hearts content. I think it is a cool device that might cause confusion until you actually use it.

I wasn’t sure how much of a difference something like this would make, but I’m genuinely impressed. The sound quality is noticeably clearer, with more detail and separation than I’ve ever gotten from my phone or laptop alone. It drives my headphones effortlessly, even the more demanding ones, and adds a sense of depth to the music that’s hard to go without once you hear it. Build quality is excellent—it feels solid and premium in the hand. It also worked right out of the box with both my phone and computer, no hassle at all. If you care about your audio experience, this is a great little upgrade.

Plugged it into my phone and used it with a pair of wired headphones. Sound came out much clearer and louder than usual, could hear more detail in music tracks. Clearly the quality is much better. The device itself has volume buttons on the side which are handy for quick adjustments. Didn’t need any special setup, just connected and started listening straight away. Small size, so fits in a pocket. Actually really cool gadget and I am impressed. Very pleased. ⭐⭐⭐⭐⭐ Would certainly recommend. Great value for the price.

The HIDIZS S9 Pro Plus DAC & Amp is incredible! 🔥 It brings out so much detail and richness in my music, especially paired with decent headphones. Smooth, balanced sound with plenty of power. Build quality feels premium, and it's super compact — easy to travel with. A real upgrade for any serious music lover! 🎼