Astell & Kern A&K PD20

Sound Analysis.

The sound analysis of the PD20 was done using various IEMs and headphones, however, I mainly focused on Jewel and ATH-R70x, while playing a selection of test tracks such as Agnes Obel’s “The Curse,” Sandro Cavazza’s “So Much Better” (Avicii remix), C-Bool’s “Never Go Away,” Ed Sheeran’s “Shape of You,” Alan Walker’s “Darkside,” Ariana Grande’s “Break Up With Your Girlfriend,” Galantis’s “Hunter,” Iggy Azalea’s “Black Widow,” Indila’s “Boite en Argent,” Dua Lipa’s “Love Again,” Counting Crows’ “Big Yellow Taxi,” David Elias’s “Vision of Her,” Michael Jackson’s “Dirty Diana,” and SaberZ “Without your love.” I had at least 150 hours of burn-in time before I began my analysis.

I prefer to describe the DAP’s sound by comparing it to other DAPs and pairing it with different IEMs/headphones, since the DAP itself doesn’t have a distinct sound. What we perceive is how it sounds through connected IEMs/headphones or the differences in sound relative to source comparisons using the same pair of IEMs/headphones. This is my subjective opinion, detailing how I hear it while analyzing the sound of the PD20.

PD20 default “unaltered” tuning has a smooth, fuller-body musical tonality, almost reminding me a bit of a tube sound quality. When listening to PD20, I hear a more laidback analog sound quality which captures the emotions of the sound, delivers a fuller note weight, gives you a more intimate musical experience which you can scale up by first going through different amp settings, and then adjust further (if you are in Class A or Hybrid) by switching between different current settings. This DAP is not for those who want to analyze the sound, want a neutral reference performance, or prefer to extract the maximum amount of micro-details. By default, you will get a natural musical tonality, so you can relax and enjoy the laid-back presentation of the sound.

To better understand the sound performance of PD20’s quad ES9027 Pro DACs and the effect of the internal amplifier, I compared its LO vs PO performance, using the neutral Brise Audio WATATSUMI amp and the OROCHI IC. Then, I stepped through different settings as I continued to analyze the PO.

PD20 LO vs PO – LO output has a more transparent, less colored sound, with more airiness up top and a more expanded soundstage. Next, taking the neutral external amp out of the equation and switching to PO with PD20’s internal amp (Class AB), the sound becomes warmer, with noticeably fuller body, more controlled sparkle up top, more note weight, and a little more intimate center-focused soundstage and imaging. Switching to Class A (Low current) expands the L/R separation, reduces a bit of coloring in mids, and adds a little more sparkle in treble, which also helps in improvement of layering/separation, as well as retrieval of details. Switching to Hybrid Class amp mode, in addition to improving L/R separation (wider than in Class AB, but a touch less than in Class A), I also hear improved imaging that gives the sound more depth. But, at the same time, Hybrid literally gives you a “hybrid” tonality between Class A and Class AB, although it sounds closer to Class A, just with the benefit of battery life improvement of Class AB. Bottom line here: PD20’s internal amp does add a noticeable analog-quality, natural, smoother coloring to the sound.

Focusing on its internal amp now, with IEMs (using Jewel) and headphones (using ATH-R70x), in either Class A or Hybrid, the change between Low and Mid current is less noticeable, but as you flip between Low and High current, there is a more noticeable improvement in technical performance, such as closer to 3D holographic expansion of the soundstage/imaging, improvement in layering and separation of the sounds, and even more expansion in vertical dynamics. To my ears, Class A/High current with DAR enabled gave one of the most impressive natural holographic soundstage expansions I heard in a while with Jewel. At the same time, it will also take the highest toll on the battery, but IMHO, well worth it for its sound improvement benefits.

Also, as I compared 3.5mm vs 4.4mm PO, the difference in power output was noticeable when you switch from BAL to SE, requiring you to raise the volume to compensate for the volume drop. And, as expected, the soundstage was narrower from SE output. The tonality remained the same.

Usually, in my other DAP reviews, I would stop my sound analysis here, but this is not just another DAP, and I wanted to dive deeper into Personal Sound Profile and other Sound Studio tools. My Personal Sound Profile changed the sound to make it more neutral and reference-like, with more clarity up top. It also turned out that EQ compensation was not the same between my Left and Right ears, and the most noticeable enhancements were applied toward the upper mids and mid-treble.

I liked this personal sound profile as a baseline for fine-tuning, but was also happy that I can adjust it further with EQ, to boost the sub-bass, add a bit more pinna gain, and a little more mid-treble boost to improve the resolution. The EQ-adjustment process here was different, and I might add, quite enjoyable. As previously mentioned, I wasn’t too crazy about using Audiosphere spatial effects, but newly introduced Acura effects were not bad at all. I found Detail Enhancer and Bass Boost to sound more natural within their first 0-15 steps of the adjustment, and noticed that with Bass Boost it worked better when lows weren’t boosted in EQ, to avoid saturation.

Overall, I found PD20 to have plenty of power and drive everything efficiently and to its full potential, regardless of whether I was using high-impedance, low-sensitivity ATH-R70x headphones, my reference hybrid Aroma Jewel IEMs, or very sensitive IEMs like VE10. But I do have to note that with sensitive IEMs, using VE10 as an example, I did have to switch from Class A (and Hybrid) to Class AB, which significantly reduced the background waterfall hiss.

Comparison.

I approached this comparison a little differently, since this is not my typical flagship DAP review where I compare to other flagships in the same price range. In every comparison, I used Aroma Jewel, ensuring volume matched while listening to the same test tracks across DAPs. Additionally, I’m primarily focusing on the differences in sound as I perceive them. These are merely quick analysis notes.

With so many of today’s DAPs using AKM or CS chipsets, I decided to focus on a few of the latest releases with ESS DACs. PD20 was set to Hybrid Amp in High current, and DAR (PCM) enabled.

PD20 (4x ES9027 Pro) vs Cayin N6iii/E203 (1x ES9039S Pro)

LO comparison: there is no LO in E203, so I can’t compare their DAC output.

PO comparison: these two DAPs don’t sound too far off; the most noticeable difference here is a slightly wider L/R spread in E203, and a bit more natural, finessed rendition of the treble in PD20.

PD20 (4x ES9027 Pro) vs Hiby R6Pro Max (2x ES9039MS Pro)

LO comparison: interestingly, I hear a noticeable difference between these DACs. PD20 has bigger soundstage expansion and smoother tonality, with a bit more warmth in the mids and slightly tamed-down treble, while Pro Max has more neutral, thinner mids and a little brighter treble. It’s almost like the 9039 Pro was tuned for a more reference performance, while the 9027 Pro was tuned for a more musical performance.

PO comparison: based on the difference between their internal amps and the baseline DAC signature, I hear a sound difference in PD20, with a bit stronger and more tactile mid-bass impact, while Pro Max has a bigger boost in mid-treble. Surprisingly, their mids sounded similar, and the soundstage expansion was not too far off.

While working on this review, I got pinged by a few people asking me how PD20 stacks up against A&K’s flagships. PD20 is a different DAP, and I’m not sure it was intended to compete against A&K’s flagships, since it stands on its own, with a strength in flexibility of customizing and fine-tuning the sound, rather than offering you the best sound tuning and technical performance. Still, for those who are curious, here is a quick comparison with SP3000M and SP4000, which happen to be two of my favorite A&K flagships.

PD20 vs SP3000M – ESS versus AKM velvet sound shows similarities in mid-range tonality, with a fuller body, smoother tuning, and more natural tuning. Bass does differ in that the PD20 gives you deeper rumble and a bit more impact. Also, PD20 has smoother treble tuning, which makes 3kM more resolving by comparison, with an edge when it comes to layering and separation of the sounds (in 3kM).

PD20 vs SP4000 – and, when moving up to SP4k, along with changes I noticed in SP3kM comparison, you will also hear more holographic imaging, more dynamic vertical expansion, and improved layering and separation of the sounds, plus a blacker background. PD20 is not going to replace the flagship SP4k. Still, it makes a decent alternative for those on a budget who prefer a fuller body, smoother tuning, and a customizable personal sound profile.