The common format are MP3, FLAC, WAV, AAC, ALAC, OGG, DFF, DSF, and more other non-common formats.

Not really. If there is no network connection provided to the amplifier, it will act as an Access Point (AP) to provide network connection to the client devices after powered up. In the WiFi setting of your mobile device, you will see the WiFi SSID "moode" displayed. You can select this SSID. The default password is "moodeaudio". However, the AP mode startup time is about 2 minutes. It will take another minute to settle down to correctly recognize the password. If the amplifier has been assigned a network connection and is successfully connected to the LAN, the startup time can be as short as 30 seconds.

You can use wired network cable to connect your amplifier to your LAN. Then, you can go to moOde Player's config->network page to set your new password.

We have used the very best components in our products. For instances, we use ultra low noise ultra high PSRR voltage regulator LT3402 to power the analog section of the DAC chip. In addition, we use ultra low noise ultra low distortion OpAmp, low thermal noise 0.1% thin film resistors, and high precision 5% tolerance metaillized film capacitors in the analog signal path. Furthermore, we use isolated ground DC-DC converter to create an analog ground plane which is isolated from the very noisy digital ground plane. The last and best reason is that our principal engineer, as well as being an experienced audiophile, has more than 25 years of experience on engineering design and high volume manufacturing.

Yes. However, there is one exception. The power amplifier IC used in PA90 requires external capacitors at the 2 pairs of balanced input pins to isolate the input signals from its internal DC bias voltages. To keep the fidelity of the analog signals, we use the German made 5% WIMA metallized film capacitors.

The HPA02A offers 3 stereo phone jacks to support driving 2 set of headphones at the same time. We have dedicated one set of jacks for high impedance (Hi-Z) headphones: the 4.4mm NDIC jack for balanced output and 6.35mm for single-ended output. However, user can only choose one. We have deliberately use a pair of audiophile grade impedance matching transformer at the output stage to optimize the performance of 600 Ohm headphones. Although we name the rightmost jack as Lo-Z, user can plug in a Hi-Z headphone without causing problem. As a result, two users can enjoy music together with one headphone plug into the Hi-Z jack and the other plug into the Lo-Z jack.

Although the HPA01A only provides one phone jack, it can drive a single pair of headphones with impedance range from 32 to 600 Ohm. Without the impedance matching transformers at the output stage, the sound will not be as warm and rich as the HPA02A's. So, if you don't plan to use high impedance headphone and want to spend less, you should consider the HPA01A.

We use the very popular Class-D stereo power amplifier chip TPA3116D2 in our PA90 design. The TPA3116D2 can output 50WPC on 4 Ohm loudspeakers with 21V DC power supply. While the DAC application circuits are shared with HPA01A, the output signals of the DAC are converted to balanced signals by a quad OpAmp IC to drive the left and right channels of TPA3116D2. We also use the inductor-less design at the amplifier's output for maximum detail. For the Class-D amplifier, the fast charging and discharging capability of the filter capacitors are critical. So, we use the low ESR high reliability conductive polymer hybrid aluminum electrolytic capacitors. As a result, the amplifier sounds detail as well as good bass.

We use BJT input OpAmps and 0.1% low thermal noise thin film resistors throughout our designs to keep the sonic characteristic being neutral or natural. In the HPA series headphone amplifiers, we use the low voltage noise, low distortion current feedback class-AB TPA6120A2. When we compared the HPA's sonic characteristic with the pure Class-A headphone amplifier HA-501, we could not tell their difference. In the PA90 series power amplifiers, we use a pair of Dynaudio Contour 1.3SE for audition. The PA90 can drive the speakers with ease. Our opinion is that the amplifier sounds natural without artificially enhanced mid-tones.

Yes, no problem for the mighty 90W Class-D amplifier with a pair of 85dB 6-Ohm loudspeakers.

We acquired a new pair of UB5 speakers last year for the purpose of 4 Ohm loading test. It specs 3-way, 4 Ohm, 85dB. The PA90 can drive the speakers easily. We figured out that this speakers need at least 40 hours to break in. After that, it opened up its sound. The major difference between this pair of speakers and the Contour 1.3 SE is its enhanced mid tone, reduced treble, and muddled bass. Fortunately, we can adjust the tonality by using the moOde Player's build-in software equalizer.

The moOde Player has build-in software equalizers. There are two types available: graphical and parametric. Since the Raspberry Pi 4B computer board is equipped with a powerful quad core ARM CPU, the CPUs can be used for digital signal processing (DSP). The moOde Player comes with a set of predefined EQ settings. So, we created 2 low-frequency signal booster setting files for the parametric EQ for your convenience: LoBoost3dB and LoBoost6dB at the center frequency 63Hz.

Since the delta-sigma DAC PCM5122 designed into our amplifiers has build-in digital filters, you should avoid another up-sampling done by the SoX software module. It is because it may cause trouble rather than enhancement.

If the application circuits design for the PCM5122 is good, its sonic performance can be as good as the AK4493EQ. We have achieved this. A couple months ago, we bought a brand new S.M.S.L. Sanskrit 10th MK II USB DAC for comparison. We plugged it into the HPA01A and configured moOde Player to use the external USB DAC. The line level analog outputs of the Sanskrit were connected to the HA-501 for audiition. We could not tell the sonic difference between the Sanskrit and our DAC.

You may consider our HPA01A or HPA02A if you want to enjoy music over headphones. Our headphone amplifiers provide buffered output of the DAC.

Yes, you can use a tube buffer amplifier together with our PA90B which provides buffered DAC output and accept external analog input.

Sony makes headphones that use this plug. If you have already owned a Sennheiser HD600 series headphone, you can buy a silver coated cable from Amazon (ASIN B081PVCV27). If you like Beyerdynamic headphones, we suggest you to do some simple modification. The desirable models are the 600 Ohm DT880 Pro and DT990 Edition. Here are the steps: 1) Acquire a pair of 3.5mm stereo phone jacks from Amazon (ASIN B06XFT3NWB), 2) Acquire a pair of headphone cable from Amazon (ASIN B08DKJ9YQ7), 3) Remove the ear pads followed by prying off the plastic retainer underneath with a small screw driver, 4) Remove the felt pads, 5) Remove the permanently attached cable, 6) Install the 3.5mm jacks. Use an electric drill to expand the hole or create a new hole if necessary, 7) Re-connect the small speakers to the pair of 3.5mm stereo phone jacks. Note: this step need soldering skill. 8) Put the parts back in reverse order. We recommend to remove the felt pads permanently for exceptional detail sound. You can put them back if you don't like the detail sound.

We have acquired a few headphones to audition. These headphones are: JVC wood cone HA-SW01 (56 Ohms), HIFIMAN HE400i (35 Ohms), AKG K702 65th Anniversary (62 Ohms), Sennheiser HD6xx, HD600 (300 Ohms), Beyerdynamics DT880 Pro (250 Ohms), and the following 600-Ohm DT990 Edition, DT990 Pro, DT880 SE, T1-2nd Gen. We also removed the felt-pads that under the protective grilles of the DT880s and DT990s. The sonic characteristics of HA-SW01 and HE400i are similar. They sound balance with good bass. However, we prefer the HA-SW01 due to its sweet mid-tone. The AKG K702 delivers detail trebles and mid-tone; but, lack of bass. While HD6XX offered by Drop seriously lacks treble, the regular HD600 presents good mid-tone with lower output in treble. The lower treble level matches the infamous public opinion "Sennheiser Veil". However, this may be a desirable feature for listening to string musics and operas. The advantage of using high impedance headphone is enhanced detail. However, the low-end non-removable stock cables and felt-pads have defeated this purpose. So, we replaced the stock cable of our DT880 and DT990 Edition with the silver plated 4.4mm balanced cable. This modification made our DT880 and DT990 Edition sound outstanding. We like these two modded headphones more than the T1 2nd Gen though the T1 sounds excellent without modification.

The simplest way is to use Apple AirPlay. The music renderer name of our amplifier is "Moode Airplay". The alternative is to share your iTune Library located in your Mac, or export your iTune library to a share drive on the LAN. If you have a share drive or NAS on your LAN, you can export you iTune library to the share drive. After that, go to confiure->library page to create the music library which will be linked to the share drive folder.

You can use Windows Media Player. The audio file format we recommend is lossless ALAC or FLAC.

Yes, we have enabled both Bluetooth and AirPlay feature of the moOde Player. You will see their identity as "Moode Bluetooth" and "Moode AirPlay" respectively. If you are using IOS devices, you can simply connect your device to "Moode Bluetooth" or select the music renderer "Moode AirPlay".

Yes, you can use either HPA01A or HPA02A. Connect the RCA connectors labelled as "Analog Output" on the rear panel to the powered speakers. The output signals are buffered by the internal OpAmps. The signal level can be either fixed or controlled by the volume knob on the front panel.

Yes, you can use one of our amplifiers. Go to moOde Player's Blue-Z menu to select the music renderer to be an external Bluetooth device.

Yes, we have added support to some USB WiFi dongles which use Realtek WiFi chipsets. The WiFi chip models are: RTL8192EU, RTL8812BU and RTL8821CU. While most of the 1300Mbps USB3 WiFi dongles use RTL8812BU, the 650Mbps USB2 dongles use RTL8821CU instead. The RTL8192EU usually sold as a USB2 300Mbps WiFi adapter. The moOde Operating System detects the USB WiFi dongle during startup. If a supported USB WiFi is detected, it will load the corresponding device driver. Please note that the inserted USB WiFi dongle should not be swapped out during operation.