In today's era where "little tails" are gaining popularity,traditional portable DAC (Digital-to-Analog Converter) and amplifiers that are "tied" to smartphones seem to be in an awkward position.It cannot be denied that "little tails" are a good choice for ordinary users who want to enhance the sound quality of their smartphones— their small size and weight do not add burden when carrying them around,and they also solve the problem of most modern smartphones lacking a headphone jack.However,most "little tails" require power from the smartphone,which affects the latter's battery life.More importantly,due to their size limitations,the shortcomings in power supply design lead to a performance "ceiling" that is not high enough.For audiophiles with higher demands,the performance potential and the richness of interfaces of portable DAC and amplifiers are still irreplaceable by "little tails." As one of FiiO's renowned product lines,although it has not been updating traditional portable DAC and amplifiers as frequently as "little tails" in the past two years,it has not stopped the pace of new product development.The FiiO Q15,as a new high-end portable DAC and amplifier in its lineup,provides audiophiles with a more comprehensive portable option.

Product Specifications:

Colors: Black,Titanium Gray

Decoding Inputs: USB,Bluetooth,Coaxial

Bluetooth Controller: QCC5125 (CPU+DSP dual-core architecture),Bluetooth 5.1

USB Controller: XMOS XU316

DAC Chips: AK4191EQ + AK4499EX

Bluetooth Formats: SBC,AAC,aptX,aptX LL,aptX Adaptive,aptX HD,LDAC

USB DAC: Asynchronous 768kHz/32bit,DSD512 hard decoding,MQA full decoding (EQ mode supports up to PCM 192kHz/24bit)

USB DAC Plug-and-Play Mode: SupportedCoaxial Input: 192kHz/24bit,DOP64

Screen: 1.3-inch full-color IPS (240×240)

Headphone Output: Single-ended 3.5mm + Balanced 4.4mm

Line Output: Single-ended + Balanced; Multiplexed headphone interface

Battery Capacity: 5500mAh high-temperature resistant lithium-polymer battery

Endurance Time: Approximately 9 hours (UAC mode,balanced output)

Output Power 1: L+R ≥ 620mW + 620mW (32Ω single-ended/THD+N < 1%)

Output Power 2: L+R ≥ 85mW + 85mW (300Ω single-ended/THD+N < 1%)

Output Power 3: L+R ≥ 1600mW + 1600mW (32Ω balanced/THD+N < 1%)

Output Power 4: L+R ≥ 340mW + 340mW (300Ω balanced/THD+N < 1%)Frequency Response: 20Hz to 80kHz (-3dB)

Signal-to-Noise Ratio: ≥123dB (A-weighted)

Noise Floor: PO < 3μV (UAC decoding,large ear mode,A-weighted)

LO < 1.6μV (UAC decoding,A-weighted)

BAL < 4.8μV (UAC decoding,large ear mode,A-weighted)

BAL.LO < 1.8μV (UAC decoding,A-weighted)

Output Impedance: < 1.5Ω (32Ω load)

THD+N: < 0.0004% (LO/1kHz/10kΩ)

Dimensions: Approximately 143.5mm × 71.75mm × 21.75mm

Weight: Approximately 305gClassic Successor

Comprehensive Upgrade

FiiO's portable DAC and headphone amplifier Q5,launched in 2018,is a very classic product.At that time,it gained widespread market recognition with its craftsmanship that was on par with international brands,rich features,and swappable headphone amplifier module design.More than a year later,FiiO struck while the iron was hot and introduced the Q5's minor revision,the Q5s.After upgrading the DAC and improving support for Bluetooth formats,the Q5s stands out even more among its peers.Due to the product's continued competitiveness in the market,FiiO did not quickly replace the Q5S.Of course,this is also related to FiiO's positioning of the Q series portable DAC and headphone amplifiers.When the flagship product Q7 of this series was launched before,it was not difficult to see that FiiO's design philosophy for this series of products was to apply new and mature platforms and technologies to them (the Q7 has a lot of technology from the M17).As the successor to the Q5s,the Q15,released more than four years after the latter,naturally adopts a large number of mature technologies that are in line with its value and have been applied in other FiiO products.

In the key DAC part,the Q15 adopts the AKM flagship AK4191EQ+AK4499EX,which is a digital-analog separated structure DAC combination that appears in portable DACs and music players that are much more expensive than the Q15.Thanks to the integration of the newly developed DWA ROUTING technology,this combination can bring better signal-to-noise ratio performance and effectively reduce noise of various amplitudes.The Q15 follows the digital core module of the series flagship Q7,including a 16-core XMOS XU316,Qualcomm QCC5125 Bluetooth chip,Ti industrial-grade Cortex-M4 processor,and audio dual crystal oscillator,asynchronous/adaptive dual-mode management.This enables the Q15 to support 768kHz/32bit,hard decode DSD512 and MQA full decoding,and provides support for high-quality Bluetooth encoding formats such as aptX LL,aptX Adaptive,aptX HD,and LDAC.

The Q15 also adopts the same analog architecture,headphone amplifier,and cooling system as FiiO's own player product M15s.FiiO has given the Q15 the name "palm-sized desktop amplifier," and its application of the desktop mode on many portable audio devices is naturally not missing.In this mode,the Q15 can sustain a maximum output power of 1600mW per channel in the super large ear mode,which is not inferior to many desktop headphone amplifiers and can easily drive various headphones in the hands of users.

Continuing the Flagship Product Design

Providing Independent Power Supply Ports

The overall design of the Q15 has the shadow of the series flagship Q7.With its strong lines and sharp edges,the Q15's panel is a bit simpler.Of course,the core display part still adopts the same as the Q7 - a 1.3-inch color IPS display,which supports bilingual display in Chinese and English.It can not only display machine status,signal specifications,and other information but also achieve various functional settings.More than 90% of the settings can be operated on the machine itself without relying on an App.The screen is well integrated with the black panel in the center of the body,and in the off-screen state,the two are integrated,with a beautiful and unified visual effect.

The Q15 has an 18:9 body ratio similar to a smartphone,and its three dimensions are slightly smaller than mainstream smartphones,making it easy to use in conjunction with a smartphone.Of course,for users of flagship imaging smartphones from various brands,there may be some problems when bundled with the Q15,because the former's protruding body with too large lenses cannot be attached to the Q15.The Q15 is also the first product of FiiO to use an AG glass back panel.Its feel is very delicate,similar to PU,but it has improved a lot in terms of scratch resistance compared to the latter,and it is not easy to leave fingerprints.It is more durable and resistant to dirt,so you don't have to worry about using it without a protective case.The buttons are located on the left side of the body,including the power on/off button,up and down track selection,and play/pause button,but the functions of the last three buttons only take effect in Bluetooth mode.The hexagonal honeycomb shape of the buttons also continues the design elements of many previous FiiO products.The top of the device features a single-knob flywheel similar to the Q7 model — it appears to be a volume knob,but it can actually perform a variety of functions.The knob can not only be rotated but also pressed,and these two operation modes,in conjunction with the screen display,can achieve volume adjustment,input selection,menu adjustment,and other operations.The logic of use is more convenient than buttons,and it is easy to get started.On either side of the single-knob flywheel are the 3.5mm single-ended and 4.4mm balanced headphone jacks,both of which can also achieve line output.

The setup at the bottom of the device is worth mentioning.In addition to the coaxial input interface with a dust cover,it provides two USB-C ports.The central USB-C port is responsible for USB decoding and charging,while the orange USB-C on one side is an independent power supply interface,specifically prepared for the desktop mode.Users can connect it to a PD charger and trigger the desktop mode,at which point it will cut off the battery and directly power the machine.The battery does not participate in power supply or charging,achieving isolation and protection of the battery,while also allowing the headphone amplifier circuit to obtain a larger voltage.At this time,the Q15 will activate the hybrid gain adjustment,with the amplifier hardware gain set to the maximum and the volume adjustment curve set to be sensitive.

On both sides at the bottom,there are also switches for mobile mode and desktop mode,allowing users to switch with one click according to the corresponding usage scenario.There is also a change in the power supply logic associated with it.Simply put,in mobile mode,when users connect the Q15 to a mobile phone for decoding,it is powered entirely by the built-in battery,without consuming the phone's battery life.When mobile mode is turned off,it defaults to drawing power from the USB data port and charging the built-in battery,which is more suitable for use when connecting to laptops or PCs.The power supply logic under different switches and usage scenarios will not be described one by one here; everyone can understand it through the following figure.

Listening Experience

The Q15 supports adjustment via the FiiO Control App.Although most settings can be achieved through its screen,there is a feature worth exploring on the App,which is PEQ.The Q15 is equipped with 7 preset tuning styles and 3 custom PEQs.Through FiiO's self-developed adjustment algorithm and interface,users can finely adjust the frequency points,gain,and bandwidth of EQ to meet personalized listening preferences.Moreover,the Q15 can use the PEQ adjustment function in both Bluetooth and USB DAC modes.When running PEQ,its sampling rate support is very high,with full format and full sampling rate support in Bluetooth,and up to 192k in USB mode.

I connected the FiiO Q15 to a mobile phone via the USB-C interface to form a bundled system and chose the Sennheiser HD600 over-ear headphones,FiiO FT5 planar magnetic headphones,and FH15 earbuds,connected to the 4.4mm balanced interface of the Q15 for listening.First,I started the desktop mode with an external power supply and switched the gain to the super large ear mode.In this state,the Q15 can push the HD600 with an impedance of up to 300 ohms in a decent manner,and it is also easy to produce good sound with the FT5.Listeners can easily feel the clear outline,a certain scale of sound field space,and natural,pure tone color presented by the large headphones under its drive.It can present rich sound details,excellent layering,and relatively accurate positioning,showing strong performance.Nowadays,high-output-power "palm-sized" devices are not uncommon.Compared with them,the most obvious advantage of the Q15 when paired with over-ear headphones is its more effortless control,and the feeling of easily driving over-ear headphones is indeed more like a desktop device.

When paired with the FH15,although the super large ear mode is not needed,I still prefer to use high gain.Compared with medium and low gain,I think it can better stimulate the potential of the earbuds,bring out excellent dynamic performance,maintain sufficient sound density,and the delicate expression of the singer's voice is not affected.The pop vocals in this combination are very pleasant to listen to,with clear imaging,a warm and natural listening sensation,especially the female voice is more pleasing and pleasant to the ear.The expression of the low frequencies is more focused on the expression of elasticity and texture,and the quantity is not particularly large,mainly for atmosphere enhancement,without being muffled.In the interpretation of instrumental music,the Q15 can well restore their timbre,and its excellent resolution makes the sound more touching,while avoiding the dry and harsh feeling,presenting a bright and vivid listening experience.

In summary,as a product that has been replaced after nearly 5 years,the Q15 has well integrated FiiO's mature and market-tested new platforms and technologies in recent years,showing the quality of a high-end portable decoding and headphone amplifier from the inside out.As a multi-in-one product with Bluetooth,USB,and coaxial decoding,the Q15 can easily connect various devices in the hands of users,meeting their various application needs in mobile and desktop scenarios.With output power comparable to a desktop device and comprehensive quality,while also considering the moderate size that is easy to carry,the FiiO Q15 provides a good choice for users who hope to balance performance and portability.