(review edited due to content error). Bluetooth is inbound only – had headphone paired to source not amp. My apologies for the error.
I was recently asked by Steve at Xtenik to review the Xduoo XP-2 DAC/Amp because he thought after my recent reviews of the XCan that I would like it. Xentik is a new venture that is aimed at carrying mid-fi and above products while promising quicker delivery and better service than others. This is my first time working with Steve, and so far he has been very amicable and quick to respond. It is always good to have another vendor in the market as competition ultimately is a win for us as consumers.
The Xduoo XP-2 falls into a class of products that is being advertised as a bluetooth Amp. What this means depends on which vendor you are talking to. In this case the XP-2 has the capability to act as a bluetooth receiver from a source device and then output to a set of wired headphones and in addition, it can be used as a purely wired amp via the 3.5mm input port or as a USB dac/amp by connecting a source via usb.
The Xp-2 came double boxed with a white outer package with graphics on front and details on rear and a black lift-top style inner box done in much more subtle tones.
The inner box is a lift-top design with a shelf the XP-2 sits on, and a compartment underneath with a wealth of cables that come with it. The XP-2 comes with 2 3.5mm cables (one 90º and one straight) for use with wired sources, and two USB OTG cables (one USB-C on both ends and the other USB-C to Micro-USB) to allow the XP-2 to connect to just about anything. It also comes with a USB cable for charging the device, a manual, and warranty card hiding in the lower compartment.
The Xp-2 is very solid and has good heft. Size-wise, it is roughly the same size as the Cayin N3. Slightly narrower than a deck of cards with a similar length. Weight is about double that of a desck of cards. While still very portable, the construction gives the user some assurance that it will withstand the rigors of pocket use. Jacks are countersunk in the face and the volume knob is well protected. Buttons and switches on the side of the player are very tactile and require an intentional push to change modes so again, worry about pocket carry is minimal. The bottom of the device has two micro-USB ports, one for charging and a 2nd for data traffic. This allows the unit to be charged while in use and prevents excessive drain from the phone when used as a usb DAC as the data line does not pull the 500ma current typical of USB.
Xduoo advertises the XP-2 as using the SA9123 USB Controller for input, and the AKM 4452 DAC chip. I found several references to opamp/buffer design in Xduoo’s advertising materials, but none specifying which components. So I did what any normal person would. I took it apart. As can be seen below, the Opamps are TI OPA1652 and OPA1662 chips with a LMH6643ma buffer following. I tried running the QR code on the bluetooth antenna (lower left) but was unable to get further than the literal translation (HNY1809001).
I mentioned the modes the device can be used in during the intro, but lets look at these in a bit more detail.
The simplest mode is as a wired Amplifier. In this mode, input is via the 3.5mm aux in/out port and output is via the 3.5mm Phone Jack. Xduoo advertises the amp circuit as having ± 5V rails for maximum drive which provides roughly 250mW @ 32Ω. I found the little unit had no problem powering most headphones including the 600Ω Beyer 990 and the T50rp which are notorious power sponges. While the t50rp couldn’t be pushed to ear-splittling levels, with the gain on high, it had more than enough power for reasonable listening levels. Most fairly sensitive IEMs and even some low impedance/high sensitivity cans will be better served by the low gain mode as high gain leaves very little usable volume control before it gets loud enough to be troublesome.
Next up, USB DAC Mode. I tested this using the iPhone 8 with a camera connection kit, an HTC m11, the Cayin N3, and the Moto Z3 Play smartphone. The Xduoo worked effortlessly with all except the Moto which refused to detect it as a USB DAC. On the Iphone and M11, all apps worked well and the unit’s battery held up well to all day work sessions. I was also able to connect the XP-2 to a Windows 10 PC and use it as a DAC/amp using the native win10 drivers.
It should be noted that the USB Dac mode can be combined with bluetooth headphones so the phone can be left in a pocket or so the user can walk around the office and not be tethered to the DAC.
The third mode is the bluetooth mode. In this case, we are using bluetooth between source and the XP-2 and the XP-2 is providing both DAC and amp functionality. In this mode, the gain switch is still in play since the headphones are wired to the XP-2 and the bluetooth connection is prior to the amp stage. (When using bluetooth headphones with the XP-2, the gain switch is bypassed). In this mode I was able to again pair the laundry list of phones and PCs to the XP-2 with no issues (even the moto works this way) and connectivity was solid as long as the XP-2 and source device remained within 5-10 feet of each other. This is nice as a few devices I have tested have suffered from cut-outs when one was in a pocket and the other not. Battery life in bluetooth mode is lessened somewhat, but it was still able to put in an entire workday (8 hours without needing a charge). (When used as a wired amp, I was able to get 2 days out of it before it cut out).
Most XP-2 controls are on the side of the unit. The exception being the on/off/volume knob on the top with the 3.5mm ports. Looking at the right hand side of the unit from left to right, we have the bluetooth LED (marked BT), the Bluetooth Pairing button, the gain Switch, and the mode selection switch and LED.
Most of these need little or no explanation, but the Select option does have a couple quirks that are worth noting. First, the unit always powers on in G-BT mode. (Bluetooth), and must be changed to R-USB mode or RG-Line in mode at startup each time if so desired. The G, R, and GR (which turns out yellow) are the designations for the LED color displayed in each mode. So when powered on, the LED always starts out green. The issue I ran into with this is that when pairing the unit using USB, most devices will not see the unit unless it is in USB mode and since powering the unit off and back on reverts it to Bluetooth, it makes using it as a portable usb dac paired to a phone a bit more fiddly than I’d prefer. A last mode memory would go a long way here if you are reading this X-duoo.
This is a tough section to write as the unit has several different answers to the question, “how does it sound?”. If used purely as a wired amp, the XP-2 does an admirable job of being colorless and doesn’t introduce any notable changes in tone. When used as a USB Dac/Amp, I did find the XP-2 to add a minor boost in the mid-bass and again in the lower treble. I have to assume this is part of the tuning of the dac itself as it was not present when used as a wired amp. When used with a bluetooth connection from source to XP-2 and wired headphones, the slight boost was again noticable. I didn’t find the boost pronounced enough to be bothersome in either case, but do think those looking for a perfectly neutral platform would want to know up front that the XP-2 does add some coloration to the sound in certain instances
I noted some of my sound references under the features discussion, but have taken a bit of a beating regarding not enough discussion of sound so I am adding the comments here as well.
The amp itself has plenty of power to run just about any can as I had no problem using both 600Ω Beyers and Fostex T50rp with its noted lack of sensitivity. I found the amp added only a slight boost to the mid-bass and gave the XP-2 a slightly warm tone as a result. This was much more pronounced when the DAC was in use. In USB and Bluetooth Source Mode, the coloration had more of a mid-bass/lower mids push as well as slightly forward lower treble giving the XP-2 a warm tone while still maintaining a forward vocal. In Bluetooth earphone mode, I found the XP-2 added very little color if any but did a great job of providing good connectivity and long battery life. I was able to wander around the office without cut-outs or breakup and easily got 7-8 hours of playback time out of the unit.
The XP-2 is a jack of many trades and does most things quite well. Battery life is impressive for a device its size, and power is more than adequate for most real-world situations. I found the XP-2 to be a very solid alternative for those interested in something like the xDSD at a considerably lower price point. The unit is no larger, every bit as solid, and other than using a slightly less potent DAC chip, offers most of the same feature set. Most of us liked the xDSD when it came out not long ago and called it an excellent value, so what do you call something that offers the same functionality at 1/3 that price? I’m calling this one “mine”, you can call your whatever you like when you get it. If you do decide to get one, I’m sure Steve at Xtenik would love to hear from you.