Sound Analysis.

Before doing any critical sound analysis, I had E01 w/N6ii on burn in for about 4-5 days playing various tracks in the loop and switching between Class A and Class AB amp modes.  Afterwards, for critical listening I used 64 Audio U18t to analyze and compare between A01, T01, and E01 modules, using my usual 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”, Counting Crows “Big yellow taxi”, David Elias “Vision of her”, and Michael Jackson “Dirty Diana”.

Switching between Class A and Class AB sounds like going from a smoother and more laidback analog flavor of A to a faster and more energetic flavor of AB.  To my ears the difference in tonality was quite noticeable due to a speed/attack of the sound, with A having a slower attack, making the sound more laidback, more relaxed, while AB having a faster attack, making the sound punchier, with notes having a faster transient response of on/off.

In more details, when comparing Class A to Class AB within E01 module:

• A: bass has a slower attack with less aggressive punch which sounds more relaxed; mids are smoother, more laid back, a bit less resolving, and with extra analog warmth; treble has a little less sparkle.
• AB: bass has a faster attack with better defined punch and articulation; mids are more resolving, with improved layering and separation; treble has more crunch with a little extra sparkle.

The overall soundstage expansion is surprisingly wide for Single Ended output, but I still found AB to expand wider while A having a little more intimate feeling.  As for the sound, E01 still has a natural detailed tonality with a balanced signature where in many pair-ups I hear extra attention to articulate bass impact, natural detailed layered mids/vocals, and well controlled treble sparkle.  Even with some IEMs where treble could get hot, E01 was able to keep harsh peaks under control without compromising resolution and airiness.

When comparing all 3 modules, here it what I hear:

E01 (SE, Class AB) vs A01 (BAL)

• E01 soundstage is wider.
• E01 mids/vocals have a little better separation and layering of the sounds.
• E01 has blacker background.
• A01 kind of sounds like it’s in between E01 Class A and AB.

E01 (SE, Class AB) vs T01 (BAL)

• The same soundstage expansion.
• E01 mids/vocals have a little more body, while T01 is leaner and has a bit crisper treble.
• E01 has blacker background.

Pair up.

For consistency, all earphones and headphones were tested in High gain and in Class AB amplifier mode which is my favorite.  Volume is noted with “v”, and please keep in mind that max volume is at 100.

Meze Empyrean (v51) – the tonality is very natural yet still quite detailed, the sound is very dynamic, layered, balanced.  Deep bass extension with a powerful impact, natural detailed mids/vocals, and natural well-defined treble sparkle.  I really enjoyed pair up of E01 with these planar magnetic headphones and found N6ii w/E01 to be a great portable source for Empyrean.

Audio Technica ATH-R70x (v64) – a very wide soundstage expansion, natural detailed resolving tonality, great bass expansion with a nice articulate punch, natural detailed mids/vocals (more clarity than usual), and airy well-defined treble sparkle.  No problem at all driving these 470ohm open back headphones, and extra bass punch was especially enjoyable.

64 Audio U18t (v31) – very natural detailed expanded tonality, balanced signature, great bass impact (very articulate), nicely layered natural mids/vocals, natural non-fatigue treble sparkle.  The sound was very natural and dynamic, and still resolving.  No hissing.

FIR Audio M5 (v31) – wide soundstage, balanced signature, deep articulate bass impact, clear and a little more revealing mids/vocals, crisp controlled treble.  The bass impact of M5 in this pair up is probably among the best I heard.  No hissing.

Campfire Audio Solaris (v20) – very wide soundstage expansion, natural detailed tonality with a balanced signature, very impressive bass impact and non-fatigue natural lower treble.  There is some waterfall hissing, less noticeable with music at full volume, and you can only hear it in quiet passages of instrumental parts of the song.  I hear this level of hissing similar to pair-up with A01 and T01.

Meze RAI Penta (v31) – wide soundstage, balanced signature, deep sub-bass rumble, natural detailed mids/vocals with a little brighter upper mids tonality. Well controlled treble with a little extra sparkle.  While Penta mids could sound a little thinner and dry in some pair ups, they do gain a little more body here, and I enjoyed them with both Class A and AB.  No hissing.

Page 3 – Comparison and Conclusion.