Sound Quality

Headphone Output

Speaker Output

Line Output

Line Input

Bluetooth

The sound quality test was done mostly using Sound Blaster X7 standard edition, with stock Op-Amps NJM2114D & LME49710, and Direct Mode set to ON (checked). Direct Mode sounds cleaner & more transparent than DSP Mode. Other setup / condition will be clearly indicated. Please take note that further sonic tuning can be done by op-amp rolling and the rich feature of DSP audio processing when preferred.for the headphone output sound quality.Clear, clean, detailed, smooth, and powerful. Very open and transparent sounding. Leaning slightly toward analytic, but in a good way, no harshness, and does not cause listening fatigue over long period. Bass is very tight, punchy and well textured. Bass is a tad leaner compared to my Yulong DA8 headphone output. Personally I do prefer for a slightly thicker and fuller mids and bass, but X7 sonic signature would match nicely with some warmer sounding headphones, such as my Philips Fidelio X1, Audio-Technica M50, & Yamaha HPH-200.Detail and transient are excellent, music feel snappy and lively, very clear and detailed. I guess the high level of detail and clarity probably useful for gaming. Overall the tonal balance is very natural with great clarity and transparency.With around 1200 mW power output @ 32 ohm, SB X7 headphone output practically drives any headphone. Headphone matching in this case is not about power, but more on the sound signature. My headphones preferences for SB X7 are toward natural to warm sounding headphones, and I prefer not to use analytical sounding headphones, especially when using stock op-amps. For analytical headphones, I recommend to replace the stock LME49710 with warmer sounding op-amp such as AD8597 or OPA827. See Op-Amp Rolling section for more detail.In comparison to the Sound Blaster X7 Limited Edition, the standard X7 has 2.2 ohm output impedance, while the X7 Limited Edition has around 1 ohm output impedance. High output impedance amplifier mostly affecting multi-way / multi-driver IEM, due to the crossover circuit, and some impedance differences between the drivers. But single driver headphones and IEMs are not prone to a few ohms differences in the output impedance.From my observation, standard edition X7 and X7 limited edition headphone output sound practically quite similar in tonality, especially when driving headphones and single driver IEM. I tried to distinguish the differences between the two, using headphones, I could only hear a very2 small insignificant differences, the X7 limited edition being a tad more open and transparent. IMHO, tonality wise only a very slight differences over the standard edition, not something significant.Even when using multi-driver IEMs such my Ultimate Ears TripleFi 10, DUNU DN-1000 and DN-2000, that supposedly should be easier to hear the difference, the sonic differences is still very small. UE TF10 gets muddy and dull on high output impedance amplifier, but that is starting slowly from 5 ohms and above. The 2.2 ohm output impedance of the standard edition is practically low enough to get great sound from TF10, and other multi-driver IEMs.Yulong DA8 is my reference DAC+Amp. DA8 has fuller midrange and bass, more body and weight to the music. Yulong DA8 also slightly smoother and warmer sounding. SB X7 has higher perceived detail and clarity, though Yulong DA8 also has high level of detail and clarity. SB X7 sounds a little analytic when compared to Yulong DA8. Imaging and spaciousness are comparable. I would say for long period of music listening with my reference headphone, Beyerdynamic T1 & Sennheiser HD800, I prefer the Yulong DA8 headphone output. But for warmer headphones such as Audio-Technica M50, I prefer the Sound Blaster X7.Similar to the SB X7, my ifi stack: ifi micro iDSD & ifi micro iCan, also use TPA6120A2 on their headphone output. Comparing to the ifi stack, SB X7 headphone output does have some similarities in sonic signature to the ifi micro iDSD & ifi micro iCan headphone output signature. They don't sound the same, but share some similarities. All have the clean, transparent, and clear sounding type of signature. Quite different than the warmer sounding amplifier or source that I have, like the Centrance DAPport, Yulong Sabre A28, and Audio-Technica AT-HA22TUBE. My Yulong Sabre A28 balanced headphone amplifier for example, is too warm for many of my headphones, and SB X7 headphone output is more natural sounding in comparison to the Sabre A28 warm signature. It is more about mix and match, and personal preference. Not about which one is the best.Coming back to the comparison with the ifi stack:Sound Blaster X7 with stock Op-Amps. Volume set to 30% at normal gain.ifi micro iDSD, Filter: Bit-Perfect, Power mode: Normal, iEMatch: High Sensitivity. Line Out: Direct.ifi micro iCan, Gain: 0 dB, line input connected to micro iDSD line output using ‘Better Cables RCA’ cable - Silver Serpent Anniversary Edition (6 inch).Headphone for this comparison: Audio-Technica MSR7LTDAll headphone outputs have been matched to around 0.25 Vrms at 0 dBFS (measured using 50Hz sine wave).On the above setup, Sound Blaster X7 headphone output sound signature is approximately in between micro iCAN and micro iDSD, closer to the micro iCan sound signature than the micro iDSD headphone output.Bass level is more or less comparable between the 3, but on micro iDSD headphone output, bass sounds dryer and harder with short decay, therefore bass doesn't sound as full & pleasant as the micro iCAN and SB X7 headphone output. Both micro iCAN and SB X7 have more pleasant bass decay, more natural sounding bass rumble and vibration without sacrificing bass texture. But both micro iDSD headphone output and SB X7 have slightly punchier and tighter bass than the micro iCAN. So for bass, I do slightly prefer SB X7 bass over the ifis, combining the punchy and tight bass with natural decay.Micro iCAN has the smoothest treble among the 3, and SB X7 treble smoothness is somewhere in between micro iCAN and micro iDSD headphone output. SB X7 treble is smoother then micro iDSD, less edgy, but micro iCAN is smoother.For midrange and vocal, SB X7 sound signature is again, in between micro iCAN and micro iDSD. micro iCAN vocal sounds smoother while micro iDSD leans to analytic.Dynamic performance is quite similar between the 3, they all have good dynamic, musically engaging and they never sounded lazy.The level of clarity, detail retrieval, spacious imaging, clear instrument separation, are all pretty close. Practically, the differences between the 3 headphone outputs are small, and require revealing headphone to distinguish the differences. With warm sounding headphones it will be difficult to distinguish the differences. All 3 headphone outputs have excellent sound quality, with micro iCan and Sound Blaster X7 are preferable over the 'rather dry' micro iDSD headphone output. And please take note, that the Sound Blaster X7 sound signature can be tweaked further by Op-Amp rolling.SB E5 and SB X7, though using the same headphone amplifier chip, but their sound signature is day and night, quite different. E5 is warmer with strong bass. X7 sounds more neutral, cleaner, more refined and spacious, slightly towards analytic with excellent clarity and detail. Bass and mids are leaner on X7 in comparison to E5, and overall slightly brighter. Hiss noise also much lower on X7 (especially standard edition), almost pitch black.2 things are important for a desktop DAC+Amp to be IEM friendly:1. Low gain setting is available to give sufficient useful range of volume control.2. Low noise output for sensitive IEM.SB X7 has 2 gain settings, normal gain and high gain. At normal gain, the maximum output voltage is approximately 2.1 Vrms, and 6.6 Vrms at high gain. With the IEMs I use for testing, useful range of volume control is up to around 40%, which is quite sufficient.Noise floor on SB X7 standard edition headphone output is very2 low. hiss noise during silent is almost inaudible even with sensitive IEM such as DUNU DN-1000 and DN-2000. Noise floor is much lower than Sound Blaster E5 headphone output. I found the headphone output noise floor on the SB X7 standard edition is actually slightly lower than the X7 Limited Edition. But there is nothing to worry about, hiss noise is still very low on SB X7 LE, still far from being easily audible. The SB X7 LE headphone output hiss noise level is about the same as the level of hiss noise I hear from ifi micro iCan, which is very low. While the X7 standard edition is surprisingly even lower, almost pitch black even with sensitive IEM. Please take note, the hiss noise is practically very2 low, and only slightly audible with very sensitive IEMs. In my case I can only detect it using DUNU DN-1000 and DN-2000. With other less sensitive IEMs in my collection, as well as headphones, no hiss noise is heard. Sound Blaster X7 is definitely an IEM friendly desktop DAC+Amp.for the speaker output sound quality using the standard 69.84 watts power adapter, andwhen using the high power 144 watts power adapter.The speaker amplifier is using TPA3116D2, high efficiency class D amplifier. With the standard 69.84 Watts adapter, SB X7 is able to drive my bookshelf speaker the older version of B&W Matrix 805 pretty loud. I would say the sound quality is decent, but not great. Clean, a bit dry, decent enough for music and movie. With the standard 69.84 watts adapter, I consider the speaker amplifier in SB X7 as a bonus feature, good to have, useful when we need it. For the price, I don't ask for more, the speaker amplifier is simply a useful feature, but most probably will not replace your high end receiver or stereo power amplifier.When using the 144 watts power adapter from the SB X7 Limited Edition, it is a different story. The extra power improves the detail and dynamic significantly. Tonality is still the same, but level of detail and dynamic improved. Music sounds more realistic & enjoyable with the 144 watts power adapter. If you need to use the speaker output, consider to upgrade the power adapter for better driving and handling capability of the speaker amplifier.Out of curiosity, I cut my stock of Mogami Neglex 2534 cable, and made a cable adapter, from the speaker output binding post to 4 pin female XLR, to connect my Hifiman HE5-LE orthodynamic headphone to the speaker amplifier of SB X7. Hifiman HE5-LE and HE6 are known to be power hungry, and perform well when driven by speaker amplifier. But the downside of using speaker amplifier to drive those headphones is the relatively higher noise floor of speaker amps will be easily heard on headphones. To my surprise, SB X7 speaker amp is dead quite on HE5-LE, and it drives HE5-LE effortlessly. It sounds very clean, and also a bit dry when compared to the warm sounding Yulong A28 balanced headphone amp that I use to drive HE5-LE. Overall, SB X7 speaker amp is pretty good for HE5-LE, though a little too bright for me. Compared to the headphone output, the speaker amplifier sounds a little edgy on the treble, but with better dynamic. But overall quite acceptable, and can be improved by op-amp rolling. Now I found the speaker amplifier of SB X7 to be a nice feature for driving my Orthodynamic headphone.for the line output sound quality.Main stereo line output is using Burr-Brown PCM1794, while the surround channels are using 2x Burr-Brown PCM1793. I didn't test the surround channels, only the stereo line output from the Burr-Brown PCM1794.Line output level is adjusted by the main digital volume. Maximum output level is the standard 2.0 Vrms. In this test, I used ifi micro iCan headphone amplifier connected to the line out of SB X7, comparing it with the sound quality of ifi micro iDSD line out. SB X7 volume was set to 100%.ifi micro iDSD is a highly sophisticated DAC, and currently my portable reference DAC. Using Dual-Core Burr-Brown native DSD/PCM chipset, the micro iDSD is capable of True Native PCM768 and Octa-Speed DSD512. Surprisingly, SB X7 DAC section, being not as sophisticated as the micro iDSD, the sound quality of the line output is not far behind the micro iDSD. In fact, by using only the stock op-amps, the sound quality is actually pretty close.Tonal balance, clarity, perceived detail and dynamic are excellent, and pretty close with the micro iDSD performance. The difference is more on the imaging & micro detail, where iDSD sounds a little more spacious with better layering and instrument separation. The treble is also slightly smoother on the iDSD, and overall slightly more refined. But overall perceived sound quality is pretty close. Considering that ifi micro iDSD is a very sophisticated audiophile oriented DAC, for the Sound Blaster X7 as an all-in-one solution, to achieve line output sound quality that is pretty close to ifi micro iDSD performance is quite a remarkable achievement. And the tonality can even be tuned further by Op-Amp rolling.I also did a comparison between SB X7 and SB X7 LE line output, they are practically sound the same, and I couldn't hear any differences. But the RMAA loop test measurement shown some differences between SB X7 and SB X7 LE on the very high frequency response (on the Features & Measurement section below). But RMAA test is dependent to the line input used to measure / record the line output. In this case, I don't know if the difference is due to the different frequency response of the line output or the line input. To my ears, both SB X7 and SB X7 LE line output sound practically the same.Line input uses Burr-Brown PCM4220 ADC, supporting audio recording of up to 24-bit/192kHz in Direct mode, and up to 24-bit/96kHz in DSP mode. The same AD converter chip as the one used in high-end audio interface TASCAM UH-7000. From my observation, it seems there is a +6 dB adjustable input gain at the line input. Frankly, I didn't expect this, as I prefer to have line input that is directly goes to ADC input without additional input gain.Standard unbalanced line input maximum input voltage is 2 Vrms. SB X7 line input can only take 2 Vrms without clipping when the input volume is set to 50%. At 100% input volume, maximum input voltage is only 1 Vrms. I guess the extra 6 dB input gain is to accommodate some low output sources. Anyway, what's important is the sound quality.I don't have precision measurement instrument to test the line input quality, so I just did a simple regeneration test, to record the line output of SB X7 using the line input. I use short 6 inches long RCA cable (Better Cables - Silver Serpent) to connect the line output to the line input. Setup:Sound Blaster X7 LE with stock Op-AmpsDirect Mode selectedLine Output volume set to 100%Line Input volume set to 50%Playback and recording using Reaper 4.7.7 (Digital Audio Workstation).Reaper device setup : WASAPIProject setting : 24 bit - 96 kHz.Thanks to my friend Leonard Cucos , he composed for me a simple drum track using Logic Pro, that I can use for testing. I did 5 regeneration recording. Generation 1 recorded from the playback of the original file. Generation 2 recorded from the playback of generation 1 playback, and so on, until generation 5. The recording is done without any effect or additional processing. No normalization, no compressor and limiter, no equalizer, no other processing.The original file of the drum track and all the recorded files from generation 1 to generation 5 can be downloaded here:https://mega.co.nz/#!uZd2XJpQ!VBl_qodc2qr0bZ-QZD3vrEnW62EZdygQlihaFlyPRMIPlease don't use those files for any other purpose than for your own observation. Please don't upload, post, or publish it elsewhere. If you need to use those files, please ask permission from me and Leonard. Thanks for your cooperation!The 35 ms delay on the recorded tracks is caused by playback to recording latency. With ASIO driver this latency could be greatly minimized. But for this test, I didn't need low latency.We can hear and see the different of the generation 5 file to the original file. It sounds like there is a mild compression in the process that makes the recorded file sounds slightly louder without increasing the level of the maximum peak. Generation 5 file sounds slightly louder than the original file. Especially the bass and midrange sound fuller on the generation 5 file. We can see the changes of the waveform on some close-ups below. Clearly shown that the waveform density gets thicker on subsequent recorded file. I couldn't verify that the changes of the waveform are mostly caused by the line output or the line input. But listening to the recorded file, the line input sound quality is surely very good, very low noise, and good enough to convert analog sources into high quality digital format. But I do prefer that the input gain can be bypassed, for the analog signal to go straight to the ADC input.I'm quite impressed with the Bluetooth sound quality. Roughly comparable to wired connection playing 96 kbps MP3 / AAC files, which is good enough for casual listening or background music. Bluetooth sound quality is still behind CD quality, mainly in detail, transient, and bass impact. But it is practical, useful, and quite enjoyable.1 thing that I found annoying is the Bluetooth connection announcement, "Device connected" & "Device disconnected". I really wish there is an option to disable it.1 thing that I found inconvenience when streaming music through Bluetooth connection from my phone is, there is no shortcut to launch the X7 control panel from the Android notification panel. It would be nice if I can quickly launch the X7 control panel from the notification panel, rather than looking for the control panel icon on the apps drawer.It would be great if SB X7 can also transmit music from Bluetooth interface, so when we connect it to Blu Ray player through SPDIF, we can use bluetooth headphone to watch movie. Hopefully it will be one of the feature in the next model.