Sound Analysis.

I analyzed D16 and PB5 sound using Aroma Jewel, UM/Cayin AP, and FirAudio RN6 IEMs while playing a variety of my favorite test tracks, such as Agnes Obel “The curse”, Sandro Cavazza “So much better” (Avicii remix), C-Bool “Never go away”, Ed Sheeran “Shape of you”, Alan Walker “Darkside”, Galantis “Hunter”, Iggy Azalea “Black widow”, Indila “Boite en argent”, Dua Lipa “Love again”, Counting Crows “Big yellow taxi”, David Elias “Vision of her”, and Michael Jackson “Dirty Diana”.  As recommended by manufacturer, I kept both devices on burn in for at least 100hrs using iBasso’s own balanced burn-in cable before I started sound analysis.

I prefer to describe the DAP/DAC/amp sound based on the comparison to other sources and pair ups with different IEMs/headphones since the “source” by itself doesn’t have a “sound”.  What we hear is how it sounds through connected IEMs/headphones or the difference in sound relative to other sources using the same pair of IEMs/headphones.  As a result, this section of the review usually has a shorter summary of what I find in the follow up sections.  Also, I’m focusing only on 4.4mm balanced output.  This is my subjective opinion, describing how and what I hear.

I hear D16 DAC/amp to have a neutral sound tuning with a natural analog tonality.  So, the overall tuning is quite neutral and linear, having a baseline sound signature without any noticeable exaggerations or enhancements in lows, mids, or treble.  While the sound is on a smoother and natural side, I don’t find it to be colored, but rather naturally transparent and resolving, yielding a great effortless pair up synergy with most of IEMs and headphones I threw at it.  What I enjoyed the most here is how well it preserved the richness and the natural timbre of instruments and vocals without any add-on coloring or bass/treble enhancement, just a tasteful addition of a more natural analog undertone.

The background is dark. and I hear a very low noise floor, super quiet with zero hiss even when using sensitive IEMs.  This makes details pop out of the blackness with natural clarity, giving a very clean on/off transition of the notes.  Also, the macro- and micro-dynamics of the recording is well preserved, with D16 being able to accurately reproduce transient changes between peaks of the sounds without compressing it.

The soundstage expansion is pretty wide, deep, and tall, being naturally proportional in all 3 directions without exaggeration.  Of course, it will depend on the limitation of earphones and headphones tuning and how wide it will spread to begin with.  But it definitely will not hinder the original technical performance, will not reduce the holographic expansion or imaging and in some cases actually enhanced it, especially when focusing on vocals.

After adding PB5 amp to the audio signal chain after D16, I can still hear a very big soundstage expansion with more enhanced width/height and a decent depth, including nearly a holographic level of imaging.  In a number of pair ups, the soundstage expansion was actually improved when adding PB5.  The technical performance of PB5 is as impressive as from D16 source, with a very good layering and separation of the sounds and excellent vertical dynamics expansion. 

Adding PB5 to a clean output of either D16 or Dx320Max Line Outs felt like adding a well-controlled coloring to the tonality but not at the expense of adding the analog “distortion” or lowering the resolution.  You can also experiment with double amping if you connect from PO of either sources to get more analog “distortion”, but directly from LO the connection was pretty clean to my ears.

When it comes to the tuning and the tonality, PB5 yields a stronger bass impact (especially in mid-bass), a warmer lower mids which give additional body and analog texture to the sound, and a little smoother treble.  As a result, PB5 colors the sound with a smoother and more musical tonality.

4.4mm BAL vs 3.5mm SE – I did try 3.5mm as well, and with D16 when switching from 4.4mm to 3.5mm, tonality remains the same; the only difference I hear is having less power, and slightly narrower soundstage.  And I found similar changes when using PB5, balanced output had more power and slightly wider soundstage, while the tonality was identical between balanced and un-balanced outputs.

Pair up.

In this section of my review, I will go over how various earphones and headphones pair up and sound with D16 and PB5.  I did note the volume setting of D16.  These are short analysis notes to give you the basic idea of what to expect.

In my setup I used DX260 as a source with D16 (DAC: HG, vol 95, AMP: LG for IEMs, HG for Headphones) and PB5 (LG for IEMs, HG for Headphones).

Pair up with Headphones.

Audio-Technica ATH-R70x (vol 12 clicks) – R70x are open back 470ohm headphones and they do need to be pushed harder to drive them to their full potential which D16 did without a problem and with plenty of headroom.  In low gain Stepped attenuator was close to max steps, but in high gain it was at 50% (12 clicks).  The soundstage is very open, wide, though having more depth/height than width.  Imaging was good, but I noticed it being more mid-centered, similar to DX320Max.  Overall, tonality is very natural, detailed, and transparent; not as reference as DX320Max, more musical in comparison.  Sub-bass is deep and textured, mid-bass is tight and punchy, very well controlled.  Mids/vocals are very clean, natural, detailed, just a little bit of coloring to give them smoother tonality.  In some pair ups R70x vocals can get warm, but not here.  Natural – yes, but not warm.  Treble also has a nice natural clear sparkle and a good extension.  A very effortless natural pair up.

– w/D16 (LO) + PB5 – soundstage now sounds more spherical, holographic, with width and depth/height being more proportional.  And the same goes for imaging, being more 3D.  I wouldn’t say exactly that I hear a big difference in tonality, just that with PB5 the sound is a bit more polished with more texture.  In pair up with R70x I preferred D16/PB5 combo.

MEZE Audio Empyrean (vol 8 clicks) – another pair of open back, and these planar magnetic headphones do sound very open and expanded with nearly 3D holographic imaging.  Didn’t like low gain, had to switch D16 to high gain which added a bit more body to the mids.  The sound sig is balanced, fast, very clean, clear, and detailed.  I hear a deeper sub-bass rumble with a little extra weight, and mid-bass punch being fast and articulate; overall bass is just north of neutral, not too elevated.  Mids/vocals have a natural, detailed, transparent tonality with just a little bit of thickness in lower mids to give them extra soulful texture, especially noticeable when I switched amp section to high gain.  Treble is crisp and airy, not harsh, or bright.  Overall, I hear a very clean detailed sound, the overall tonality is transparent, though there is a touch of warms in lower mids.

– w/D16 (LO) + PB5 – soundstage is as wide open and holographic with 3D-like imaging as it was directly from D16, though now some of the percussion sounds almost wrapping around me, like they are coming from behind me.  Difference in tonality adding PB5 to the sound chain is more noticeable here.  The mids gained more body, more warmth, more texture, especially noticeable when focusing on vocals.  Also, I hear more rumble in sub-bass.  In pair up with Empyrean I definitely preferred D16/PB5 combo due to a noticeable improvement.

Beyerdynamic T5p 2nd (vol 6 clicks) – despite these being closed back, soundstage was very open and exceptionally wide.  The sound is very clear, with tonality being clean and detailed.  Bass has a deep textured rumble with extra weight, mid-bass has a fast well-controlled articulate punch.  Mids/vocals are natural, transparent, and a bit more revealing in upper mids, but not too bright.  The treble is clear, airy, not harsh, with a great extension.  In this pair up, again, I felt like mids very shining while being less colored.  In many other pair ups T5p 2nd end up having a brighter treble and more neutral sub-bass, while here it was driven to perfection, similar to DX320Max but with a bit smoother, more natural mids.

– w/D16 (LO) + PB5 – soundstage is as wide open and holographic with 3D-like imaging as it was directly from D16, don’t have too many changes in staging while going from D16 to after adding PB5.  Similar to Empyrean, the difference in tonality while adding PB5 to the sound chain is more noticeable here.  The mids gained more body, more warmth, more texture, again, very noticeable when focusing on vocals.  Also, I hear more rumble in sub-bass and stronger punch in mid-bass, with the bass scaling up in weight and impact.  In pair up with T5p, I definitely preferred D16/PB5 combo due to a noticeable improvement as well.

Pair up with IEMs.

Aroma Jewel w/FT (vol 7 clicks) – The soundstage has wide expansion with slightly more depth.  Sound signature is very balanced (W-shaped), with a natural detailed tonality and a balanced presentation of the sound.  Bass goes deep, has a textured sub-bass rumble and a punchy mid-bass; the bass is tight and articulate.  Lower mids are a bit north of neutral, adding extra body to the sound.  Upper mids are natural, detailed, resolving, not too bright, but with plenty of clarity and excellent retrieval of details.  Treble is crisp and detailed, but still natural.

– w/D16 (LO) + PB5 – the sound expands in soundstage, becoming more 3D holographic.  Mids have more transparency, and to my big surprise, having less coloring in comparison to being connected directly to D16 PO.  So, I preferred Jewel connected directly to D16.

Empire Ears Odin (vol 5 clicks) – I can confirm a pitch-black background with no hissing.  The soundstage here is huge, and the imaging is on holographic level.  Bass extends deep with a textured rumble and a tight fast mid-bass punch.  Lower mids are a bit south of neutral, leaning toward the “leaner” side, while upper mids are more revealing, very detailed, a bit more forward in presentation.  Treble is crisp, clear, detailed, more revealing, but not splashy.  The overall sound is leaner and more revealing, having a bit more analytical presentation.

– w/D16 (LO) + PB5 – still no waterfall hissing.  The sound soundstage/imaging are the same.  The tonality is still revealing, but more natural rather than analytical. I preferred Odin with D16/PB5.

FirAudio Radon 6 (vol 4 clicks) – A big holographic soundstage expansion, actually quite wide though I feel there is more depth/height with the sound projecting a bit more out of my head.  Unlike some other sources paired up with RN6, this one has a more balanced signature, though you can still hear and feel a deep and a powerful speaker like bass impact, being just a bit forward.  Natural detailed mids and organic vocals don’t feel recessed behind the powerful bass.  Treble also sounds crisp and natural.  I’m always on the fence describing sound sig of RN6 due to its powerful bass.  Here, the sound does feel balanced with an elevated bass which doesn’t overpower mids too much.

– w/D16 (LO) + PB5 – soundstage now sounds more spherical, with width and depth/height being more proportional.  Bass is still as powerful, gaining a bit more rumble, treble sounds the same, but I noticed mids/vocals coming up in quantity with slightly more forward presentation of their natural detailed tonality.  I enjoyed both pair ups, with and without PB5.

Vision Ears VE10 (vol 2 clicks) – With VE10 being one of my more sensitive IEMs (Campfire IEMs are currently still on loan to another reviewer), I do have to mention there is hardly any waterfall hissing.  The soundstage expansion is pretty big, rounded, and the imaging is quite holographic as well.  In this pair up VE10 has a balanced sound signature with a smoother natural detailed tonality.  Sub-bass rumble and mid-bass punch do have a little more weight, mids are very natural and detailed, and treble is a bit more accentuated, nothing exaggerated, just to give the sound more crunch and to improve the overall resolution of the sound.  In some pair ups VE10 could sound warmer, but here it gains a bit more transparency without losing its musicality.

– w/D16 (LO) + PB5 – waterfall hissing was a bit too strong for my ears due to sensitivity of these IEMs, so I skipped this test.  Obviously, D16 pair up only.

Page 4 – Comparison, Source pair up, and Conclusion.