X7ii new sidekick – AM3A module.
Revealing of the latest X7ii DAP introduced many external and internal design changes, including a new AM3A balanced amp module which comes standard with this new FiiO flagship. I’m sure many still remember the original X7 with its stock AM1 module which didn’t exactly raise the bar, until we saw follow up releases, including balanced AM3. Having a modular design is a big plus, but you can spoil the first impression with an average sounding amp. That’s why I’m pleased FiiO took it seriously this time, and aligned introduction of their new AM3A with X7ii release. This amp module is still fully backward compatible with the original X7, just like any of the AM# modules from X7 being fully forward compatible with X7ii. With a new X7ii you just need to apply the external aluminum trimming piece to match the shape of the new design.
When AM3A and X7ii were announced, I received a number of requests from my readers asking how does its BAL (2.5mm TRRS) compares to SE (3.5mm TRS) headphone outputs, and how does it compare to the original balanced AM3 module. This is going to be a short review, which I figured makes more sense to share on my blog instead of writing the same reply in multiple posts. Of course, the full X7ii review will be posted in a near future and you can expect in-depth analysis and comparison. For now, just consider this as a teaser, focusing specifically on AM3A.
From the exterior design perspective, AM3A is identical to the original AM3; just like other amp modules the only difference is in a color shade. As I mentioned before, all FiiO amp modules are interchangeable and fully compatible with both X7 and X7ii DAPs. From outside, you still see a micro-USB port in the middle and 3.5mm TRS Single Ended HO port on the left and 2.5mm TRRS Balanced HO port on the right. But that’s as far as similarities go, because inside it’s an all new design with a different spec.
According to FiiO, the original AM3 amp module uses six OPA1622 TI (Texas Instrument) SoundPlus audio op-amp ICs with a following spec (I’m quoting only the power at 16 ohm load):
2.5mm – 420mW @ 16ohm, 0.3ohm impedance, 115 SNR, recommended 300ohm drive, max Vout 11Vpp
3.5mm – 250mW @ 16ohm, 0.3ohm impedance, 115 SNR, recommended 150ohm drive, max Vout 7Vpp
AM3 block diagram
The new AM3A amp module switched to high precision Analog Device AD8620 op-amp, and exclusively designed OA926 op-amps:
2.5mm – 380mW @ 16ohm, 1.7ohm impedance, 119 SNR, recommended 300ohm drive, max Vout 10Vpp
3.5mm – 200mW @ 16ohm, 1.2ohm impedance, 116 SNR, recommended 150ohm drive, max Vout 6Vpp
AM3A block diagram
You can see right away, on paper they are not the same. The output power has decreased while the output impedance went up. At the same time, SNR ratio has improved.
The power is lower now, which I expect to be reflected in some very marginal battery life improvement. Less power usually also means less hissing with sensitivity IEMs. While testing X7ii with TIA Fourte (10 ohm, 114dB sensitivity, using 1960 2wire cable with 2.5mm TRRS termination) and switching between AM3 and AM3A while keeping the volume down to 0 and hitting Play – the hissing level remained the same but I do hear AM3A to be “cleaner” without any crackling interference as I do hear with AM3, perhaps due to a better shielding and power filtering in AM3A.
Another important note, with volume back to a normal listening level, the output impedance of 1.7ohm (AM3A) vs 0.3ohm (AM3) had almost no effect on the sound tonality. I was closely monitoring changes in low end impact and upper mids/lower treble brightness, but the sound was very close, which suggests that regardless of a different op-amp selection, these amp modules have a similar transparent sound characteristics.
So how about high impedance, more demanding cans? X7ii with AM3A drove ATH-R70x (470ohm, open back) with a full authority and still had some volume headroom to spare:
in low gain – 101/120 (max volume 120).
in high gain – 85/120 (max volume 120).
I don’t have full size cans like HD650 to use for testing, but R70x is not an easy pair of headphones to drive and with many other DAPs I push it closer to max volume in high gain.
I know that sometimes we are quick to judge the product on paper, but it’s better to give it a listen before drawing a conclusion.
Looking at the spec of AM3, it’s clear that a difference between its SE and BAL outputs will be mostly in power. That’s exactly what I confirmed in my testing. In terms of sound quality, the performance between these ports was quite similar, just different in power output.
With AM3A, the difference between SE and BAL ports is more noticeable. Obviously, BAL will have more power and it took me about 9 clicks to match the volume when switching to SE. Another noticeable difference is soundstage expansion of BAL output being wider than SE. Also, I can hear a blacker background with a cleaner on/off transient of notes with BAL output in comparison to SE. Perhaps improvement in SNR of AM3A BAL output is to thank for this, and it was more noticeable when playing hi res files with revealing IEMs.
When the original X7 was released, there was a lot of anticipation and some people felt underwhelmed. It was their first Android DAP with introduction of a modular design and dual OS. Ever since that release, FiiO came a long way, improving firmware, releasing new modules, introducing X5iii, and now releasing their updated second gen X7ii. To me personally, it felt like this is a third gen release because X5iii felt quite mature, like a next gen after X7 (relative to build and design). So far, X7ii feels like a solid release which took everything FiiO learned from their freshman X7 release, including all the firmware updates, and all the design lessons they learned from X5iii (moving the power button to the top is a plus in my book!). The result is a polished product that already performs quite nice right out of the box.
When comparing AM3 vs AM3A, you have more power (AM3), blacker background (AM3A), AM3A SE has a touch wider soundstage than AM3 SE/BAL, and AM3A BAL has the widest soundstage. Can you consider that as an improvement? If you have the original X7 with a stock AM1 module and thinking about upgrading to balanced, I would go with AM3A. If you have X7 with AM3 already, I don’t think it makes sense to upgrade to AM3A, the change is not exactly night’n’day since I hear them both having a transparent sound and a similar tonality.
I think FiiO finally recognized the importance of making a positive “first impression” and made the right decision to include stock AM3A amp module by default with their new flagship X7ii DAP which still maintains an impressive price/performance ratio.
Comparison of X7, X7ii, and X5iii