xDuoo XD05 Plus – powerful and functional portable DAC/amp

Welcome the new adept of xDuoo portable DAC/amp series 🙂 Just can’t stand sharing the overall impression pertaining to the conclusion at the beginning of the article. Some companies deserve the appreciation for their remarkable product with outstanding combination of clever R&D, functionality and smooth performance. Like with xDuoo XD lineup – it is the love from the first sight – starting with the design and ending with the feel of a great bargain.

Short note about xDuoo company:

Shenzhen xDuoo Technology Co., Ltd. is a professional company specializing in the development, design and sales of high-end audio products. We have a strong technical team with professional knowledge background and unique tune tuning audio method, and we have been given many well-known brands ODM for many years and won good reputation and trust. While developing and growing, the company has carefully created its own brand and successfully launched it to the market, which has won wide acclaim. Our products involve headphone amplifiers, audio decoders, USB interface audio decoders (PCHiFi), various types of power amplifiers, audio players, etc. The total number of products designed is more than 100 models, and we have a number of patented technologies that can meet the needs of users.

This is not the first experience with xDuoo for us – we have been playing with very popular X series DAPs several years ago. First DAPs were so popular for its price/performance/functionality ratio that has grown the community and driven some individuals to develop third-party firmware that pushed the functionality and sound quality even further. Yep, such builds were also addressing some initial software flaws in first iterations of the product as well as weak technical support, but at the end – the hardware part was functional, allowing end-user modifications and software enhancements. Later DAP models, according to the end-user feedback, granted the expected maturity and polished performance by utilizing more common operating system and market standards.

With XD series of DAC/amps everything is other way around – you get a perfect product from the box with the possibility of further customization if you would dare to make one. XD05/XD05 Basic/XD05 Plus are so widely used that those are very frequently spotted in feeds of various Facebook audio communities, on forum pages and articles, in sound quality test and comparisons and listed in almost every single online audio equipment store worldwide. Integrated to home audio systems, used as shelf or portable DAC/amp for headphones, earbuds and IEMs, aiding smartphones, laptops, PCs and tablets – XD05 run good in most scenarios, make these possible, left as it is or being heavily modified by users. The good thing is that xDuoo constantly monitors such feedback and takes it into consideration for their future products which is apparent from the functionality and convenience of operation.

Back to the topic – xDuoo XD05 Plus – which is the flagship in the lineup of portable DAC/amps for now.

XD05 Plus specifications:

• Compliant operating systems: Windows XP/7/8/10, Mas OS X, IOS, Android
• Screen: 0.91″ OLED
• Buttons: Input, Source, Filter
• Switch: Boost, Bass, Gain
• DAC chip: AK4493EQ
• USB chipset: XMOS XU208
• Coaxial/optical chip: CS8422
• FPGA: Altera-EPM240T
• Signal AMP: OPA1612
• Circuit AMP: BUF643U
  • USB (PCM): 16–32bit / 44.1–384kHz
    • DSP: DOP / NATIVE mode, DSD64–256 (1bit / 2.8M–11.2M)
    • DXD: 24–32bit / 352.8K–384kHz
  • OPT/COA (PCM): 16–24bit / 44.1–192kHz
    • DSD: 1bit / 2.82 Mhz (DOP)
• Output power: 1000mW at 32 ohms
  • Frequency response (amp): 10Hz~100kHz (±0.5 dB)
  • Frequency response (USB/SPDIF): 20Hz~20kHz (±0.5 dB)
  • THD+ N (USB/SPDIF in): 0.0016% at 1kHz
  • THD + N (aux in): 0.0009% at 1kHz
  • S/N: 117dB
  • Crosstalk: ≥75dB
• Inputs: Coaxial/optical 3.5mm, Aux 3.5mm SE, USB type-C
• Outputs: Headphones 6.3mm, Aux 3.5mm SE
• Charging port: USB type-C
• Battery: 3.8V / 5000mAh
• Battery life: ≥13 hours (USB in), ≥21 hours (SPDIF in), ≥40 hours (aux in)
• Size: 139.5*75*23mm
• Weight: 276g

xDuoo Xd05 Plus available at the official store: HERE

Couple of words about the difference between XD05 / Basic / Plus versions: Plus, as already mentioned, is the most expensive and most advanced option. Main (but not all) differences of Plus with other two are:

• More advanced AK4403EQ DAC chip (instead of AK4490)
• Type-C ports for USB input and charging (instead of micro USB and type A)
• XMOS XU208 chip (instead of U8)
• DSD 64 (DOP) support over Optical/Coaxial input (new feature)
• Double DIP-8 Op-amp sockets, easy swappable, comes with single Op-amp OPA1612 in socket adapter
• 1000mW @ 32Ohms (instead of 500mW)
• 5000mAh battery (instead of 4000mAh)
• Better THD+N and SNR specs

Therefore, Plus version is quite better than both of its predecessors, especially by its outstanding output power, playback time and possibilities to change Op-amps for custom sound experiments easily. Although, we should state that there is one significant (but not vital) drawback – Plus version, in contrary to Basic or initial XD05 does not feature External / Battery power source switch any longer. It means that if you would use it as a shelf DAC/amp with permanent connection to wall outlet – it would lead to fast battery deterioration (since it would be constantly left on charge, which is very bad for any type of battery).

Packaging and design:

xDuoo XD05 Plus comes in a beautifully designed box with shiny schematic device outlines in blue (outer cover) and glossy black (main box) with lots of product information imprints. Inner box compartment consists of two levels with the amp resting in special cutout of the soft insert on top and rest of the product accessories located underneath.

Box contents consist of the following:

• XD05 Plus DAC/amp
• Short angled USB type-C -> micro USB cable
• Short angled USB type-C -> type-C cable
• Long USB A -> type-C cable
• 2 special pins for 3.5mm input/output protection
• 10 pairs of silicone stand offs
• silicone pad
• 6.3mm -> 3.5mm jack
• 4 spare screws
• user manual and warranty card

Unfortunately, haven’t found any rubber band to hold the sandwich together when you want to use DAP and XD05 on the go. Neither there are coaxial, audio or optical cables included. Glad to have silicone legs and spare screws in this package since shelf usage and experiments with Op-amps are definitely among our intentions in future.

Design of XD05 Plus is the first virtue you would love it for. It is clean, modern and functional – perfectly fits its purpose. We would also call it military – it reminds us of a weapon: burnished metal appearance, cold feel of a gun and AK47 style barrel vents on the edges. Really appealing to men, either looking at or holding it. Feels very solid and rigid, thanks to the excellent build quality, rough surface finish, choice of material and precise manufacturing process.

The shell is made of a single piece of aluminum profile with front and back covers held by 4 torx-type screws. Top, bottom and right side are free of any controls but have some imprints: logo on top and left side button label at the bottom.

Back side includes all communication ports (3.5mm Coaxial/Optical input, Aux 3.5mm input/output, type-C USB input, type-C USB charging port) and status LEDs (red for charging, blue for USB data reception).

Facing side consists of 6.3mm headphone output, 0.91″ OLED screen, volume knob with integrated power switch, two 2-position switches (Boost, Bass) and one 3-position switch (Gain). SRC, Filter and Input buttons are located on the left side. Vent openings on both sides are designed to dissipate heat produced by the board elements, therefore – should not be covered.

Now, let’s take a look at the internals.

Easy to open – just unscrew 4 screws on the front panel and pull out the entire board from its shell. Shell has guiding slides for the board while the board has one springy ground pin at the bottom and similar pin at front. Be careful not to damage the bottom pin when sliding it back in place.

Board is accurately populated with high-quality elements, all are well-aligned, soldering is neat, no signs of flux spills. Here you would find all declared chips of dac, amps, and processors. Single OPA1612 op-amp uses 2 slots with the adapter and can easy be swapped to other model, either single or paired. Great that the battery is not soldered to board and uses 4-pin connector instead. This is a peculiar thing: it is labeled as 3.8V (seems to be LiHV type of cells) 5000mAh but consists of 2 cells (in parallel, 4 wires connection). Usually, each cell have similar label or a set of cells has the summarizing label. In first case we would get 3.8V, 5000mAh X 2 (since in parallel) = 3.8V, 10000mAh. Or, if it means the set, we should have 3.8V, 2500mAh/cell but the label should state “2P”. Since xDuoo declares that XD05 Plus has 3.8V, 5000mAh battery – than, it is the second case but “2P” was not stated.

Back to the warning that there is no external / battery power switch: since there is no switch – shelf use with constant charging cable connection would cause fast battery deterioration. We doubt that xDuoo has implemented smart charging circuit when the device is powered from the external source which would omitt battery charging when the charge gets full. Neither XD05 Plus works when the battery is removed. Therefore, the only way to get rid of the battery is to make power source + capacitors with 4 pin adapter and supply voltage directly to battery connector.

Op-amps: for now we have stock dual TI OPA1612 and we are pleased with the resulting audio quality. But people report that they are even more pleased with Burson V5i or 2 x single Muse 03 op-amps.

Device in use:

First of all, the battery should be charged. Since XD05 Plus comes with no wall charger – you can use stock USB -> type-C cable with any 5V adapter. It would take about 4.5H to fully charge XD05 Plus battery. xDuoo states 4.5H fast charge and 11H for regular charge. Not sure what do they mean by that but in our understanding it is not about fast charge technology, but the output power of the charger. If it takes 4.5H than the charger should be able to supply ~1.5A for 5000mAh battery. Fortunately, XD05 Plus can take charge and function simultaneously. Red LED on the back would be lit throughout the charging process and gets off when done, no matter XD05 Plus is powered on or off. If it is in ON state – it would also indicate charging process with on-screen battery level. No excessive heat of the shell is spotted during charging, thanks to large aluminum chassis and enough room inside.

Further steps would depend of the main usage intentions. There are lots of scenarios XD05 Plus can be used at, some requiring the additional cables and some are good to go with the stock bundle. Let’s consider each one:

• Using it as external DAC/amp for DAPs / Android smartphones & tablets / Windows based PC / laptops with USB A or USB type-C ports for headphones/IEMs/earbuds: no additional cables needed. Only ASIO driver in Windows environment for the best audio quality (can be downloaded from HERE).
• Using it as external DAC/amp for iOS smartphones & tablets / MAC based PC / laptops for headphones/IEMs/earbuds: additional Type-C -> Lightning cable needed. (can be purchased on the official product page together with XD05 Plus or separately HERE).
• Using it as external DAC/amp for any source over Optical/Coaxial for headphones: additional Coax/optical -> 3.5mm Coax/optical cable is needed
  • To use with active speakers or as preamp for home amplifier: you would need one more 3.5mm Lineout -> active speakers/amplifier cable
• Using it as external amp for any source with 3.5mm line out -> XD05 line in -> headphones out: additional 3.5mm -> 3.5mm cable is needed
  • Using it as external amp for any source with other types of analog line out -> XD05 line in -> headphones out: additional corresponding line out -> 3.5mm cable is needed

Therefore, the main usage scenarios cover most of the types of use, including DAC function of XD05 Plus or excluding it and running it in amplifier mode alone. In this case, the output is possible only to headphone port since the Line out and Line in are combined and occupied by the input from a source. We wish that those outs were separated to a different ports to be able to use XD05 Plus as preamp for a DAC in home setup. It still can be used this way by feeding headphone signal to home amp, but this requires accurate tuning of volume level and care about the position of front switches.

Android-based smartphones and tablets, as well as most of the DAPs won’t have any problems with connecting XD05 Plus as external DAC/amp over USB. It would be better to use some applications such as HiBy Music that are capable to provide bit-perfect data stream directly to USB device while omitting OS audio processing. DAPs would do the same with its DTA architecture or proprietary OS builds. In Windows environment, it is better to use the ASIO driver provided by xDuoo to fully utilize the device features. Although, native Windows 10 driver detect xDuoo correctly and allows 32bit/384kHz as well. Both drivers have virtually no audio lag while watching videos. Perfect.

To summarize this section – every single tested scenario went smooth, with not a single hiccup from XD05 side. DAPs, smartphone and laptop didn’t hang even once during the tests despite large amount of reconnections during the tests, different types of interfaces used and fast swaps of tracks with different audio quality and formats. Perfectly polished user experience and reliable, glitch-free performance.

Controls:

Really love volume knob on XD05 Plus. We’ve seen it one that someone has reported channel imbalance on low volume level but our unit is free from that flaw. Tangible power ON/OFF click, tight rotation, precise position, no rattling whatsoever. Volume starts from almost quiet to full, increases smoothly, utilizing ~90% of rotation. No harsh popup sound when the power is turned on/off. Just to mention 1W of power: for example, AudioTechnica ATH-M50 (38Ohms impedance, 99dB sensitivity) is driven loud with 50% of volume knob rotation (Gain and Boost switches at minimum position). Gain Mid / High can damage such overheads easily at max volume. More sensitive headphones/IEMs and earbuds with lower impedance might be burnt easily even in Gain Low at high volume levels. Therefore, be careful with Gain switch and do not change its position accidentally.

Front switches also feel nice and tight to operate. Boost stands for 2 position impedance switch (low = <150Ohms, high = >150Ohms), Bass is responsible for boosting lows/midbass and Gain does what expected in 3 significant changes in its level. Left side buttons serve to scroll through inputs (Input), upscale coaxial/optical input stream (SRC) and to change PCM/DSD filters (Filter):

• Sharp roll-off (PCM1 on screen)
• Slow Roll-off (PCM2 on screen)
• Short delay Sharp (PCM3 on screen)
• Short delay Slow (PCM4 on screen)

Filters in DSD:

• 39Khz = DSD64 at DSD1 (on screen)
• 78kHz = DSD128 at DSD1 (on screen)
• 156kHz = DSD256 at DSD1 (on screen)
• 76kHz = DSD64 at DSD2 (on screen)
• 152kHz = DSD128 at DSD2 (on screen)
• 304kHz = DSD256 at DSD2 (on screen)

Filter, source as well at the sample rate would be indicated on screen. The screen, on its turn, is quite small but totally good for its purpose and bright enough to be seen in shady conditions. Having the screen in such device is not that necessary imbut adds to the functionality and convenience. Not saying that it also adds to the overall value and satisfaction of using XD05 DAC/amp series.

There is one more thing that makes XD05 Plus even better – possibility to connect add-on Bluetooth module XD05 BL (fits Plus and XD05) that would turn your device into Bluetooth receiver with SBC, AAC, aptX, aptX-LL, aptX-HD, LDAC codecs on board. This module would occupy Coax/optical and line 3.5mm input ports.

Sound test:

Our sound setup during the test: HiBy R5 Sabre DAP + xDuoo XD05 Plus + AudioTechnica ATH-M50 + ArtMagic DH3 IEMs + Edifier M1100 active speakers.

XDuoo XD05 Plus feels quite linear in its delivery throughout the entire range, not showing significant peaks or accents until requested with bass boost or gain switches. At lowest switch settings, sound feels well-balanced with quite deep, contoured, energetic lows and good amount of textures, great midbass control, power and dynamics. With the bass boost this portion gets brought forward, the increase is evident but lows loose contours and become quite moody.

Even rendering of male and female vocals in mids, free of peaking notes and harsh presentation. Mids also exhibit quite high level of resolution, pleasing thickness, excellent instrument separation and legible mix. Treble part is not accented, neither underpowered. Enough of clarity, good extension, great amount of tiny details. Sounds impressive when paired with BA/piezo driver IEMs. With higher gain settings treble might get a little bit harsh, resulting in unwanted sibilance with low impedance IEMs.

Furthermore, changing Bass boost and Gain switch settings to anything from low, to our liking, makes sound worse than XD05 Plus is capable of. When set to min – it sounds very balanced and delicate. And of course, those switches have no impact on line output. Another great aspect of XS05 Plus sound is the stage size – it builds a perception of large and especially wide imaginary stage with large distance between the instruments.

In overall, the sound of XD05 Plus is mature, full-bodied and balanced, slightly leaning towards warmer presentation. The closest DAP that we once tested is HiBy R6Pro but the amount of power and driving ability is much higher with XD05 Plus. It sounds very good across the entire range, reveals lots of details and renders large stage. Perhaps, experimenting with other Op-amps might make it sound even better but we are pleased with the stock combination.

In comparison to Hidizs Sonata DH1000:

DH1000 has many things in common concerning the usage scenarios and sound quality. It is not that advanced as XD05 Plus since less powerful, doesn’t allow Op-amp change, doesn’t act as pure amplifier, cannot accept data through coax / optical inputs. But it has balanced circuit and output and sounds quite close with the same headphones. Similarly balanced and detailed, brighter, though. xDuoo XD05 Plus is just a better bargain if to consider all of its features and specs.

In comparison to Tempotec Serenade iDSD:

iDSD is designed for shelf usage only. It doesn’t have battery, better to be used as a DAC/preamp for home system for its limited power headphone output. But it also gives the possibility to experiment with other op-amps and delivers balanced and detailed sound. We would say that if the will is to have shelf DAC/preamp only – iDSD would do. But again, it is not a competitor to XD05 series versatility, power and functionality.

Conclusion:

We are in love with xDuoo XD05 Plus, its features, specs and possibilities it delivers. Excellent design and decent build quality, connectivity options with full processing power on all inputs, good set of accessories, high power output… And last but not the least – excellent sound with good resolution and wide soundstage. All of that makes the impression of having mature and highly functional device that builds a confidence in a great bargain among other options. Add here op-amp customization feature for the most conscious fans – and you are getting the ultimate device, able to initiate a whole new movement, that would definitely settle down for long in various setups.

xDuoo Xd05 Plus available at the official store: HERE

PS: xDuoo has announced the launch of XD05 BL DAC/amp with 4.4mm balanced output along with 6.3mm SE output, revised controls, more decoding power (32bit/786kHz, DSD512) and, probably, inbuilt Bluetooth module. It also would have external/battery power switch back. But the expected price is ~$429 which is significantly higher than $289 of XD05 Plus. Therefore, if balanced output is not that important for you – we are still considering XD05 Plus a better bargain for its lower price.