If there is interest as I've seen several comparisons on this thread earlier, but not too many since newer members have joined in.
So at the risk of being a little repetitive, posting my impressions of the Q5 vs Q5s and various FiiO AM3x amp combinations, all of which are my opinions only so your mileage will vary.
I own both the Q5 (with AM3A and AM3D) and an Q5s (With the AM3E and AM3D amps)
I've owned other amp/dac combos also but to keep this simple, will just review these 2 against each other.
I prefer to run these via a direct USB cable connection vs. Bluetooth as I think I here a difference, so you won't see a comparison of Bluetooth connections here. I use it once in a while but prefer the direct cabling and passing just the digital O's and 1's for sound.
I choose traveling this way vs a DAP as the way Android sorts and presents music files just always drove me crazy, so using my PC, or other devices to just present the digital source to feed a DAC/AMP combo is just my preference.
I moved to the Q5s as Vs. the Q5 as it was smoother and more musical overall, but find with the IEM's I own (Shure SE846 and JH CIEM Roxanne's) as well as others I've borrowed (Noble K10 and Kahn) I have to use the higher gain setting Vs. the Q5 to get the overall sound I like vs. the Q5 (which sounds harsh with the high gain setting).
As far as amps/sound for both
On the Q5 there is a marked difference moving from the AM3A to the AM3E, and almost the same amount of sonic difference then going from the AM3E to the AM3D.
The AM3A to AM3E was huge. Much wider soundstage, better and clearer mids. Anyone who owns a Q5 and wondering if changing from the AM3A makes a difference all I can say is "yes".
Moving from the AM3E to the AM3D on the Q5 there was as notable of a change.
Most notably were the mids and highs. The mids were smoother, and the highs were a little clearer and seemed to have more sparkle. Soundstage also widened.
The Q5 with the dual AKM 4490EN DAC's always had great bass with lot of low end rumble, whether the bass boost was engaged or not.
With bass friendly IEM's like the SE846 and its low pass physical filter, you get a real subwoofer rumble and great clarity.
For the Q5s, it didn't make sense to try the AM3A on it, so I only tested the AM3E to the AM3D.
As noted above, moving to the High Gain setting seemed to open up all of the IEM's I tried. In the low setting, there was good sonics, but IMO there seemed to be a vail over highs and the sound overall seemed to suffer some presence. Moving to the high gain setting, everything just sounds right. Much clearer, and better separation of instruments across the soundstage.
With the AM3D there was better extension on the highs, and they were smoother, perhaps a touch wetter than the dry highs with less sparkle of the AM3E
but most notable were the mids. At first it tricks you as with the AM3E the mids are much more forward/in your face. It creates the illusion of having a wide soundstage as you can pick out specific instruments and the vocals are right up front.
Moving to the AM3D the mids are not quite as "in your face" but they are there, blending in nicely with the soundstage. Its not until you really listen that you start to hear things and can place where instruments and vocalist really are that you realize it does have a wider soundstage, and the sound is more natural and balanced vs the AM3E.
The bass on both with the Q5s and the newer AKM 4493 EQ DAC's are about the same. Maybe a little smoother in the mid bass with the AM3D. Nothing to be ashamed of, but in the area of bass, the Q5 seems to have a tad bit more slam, than the Q5s. Not much of a difference unless listening for specific bass/sub bass notes or rumble. Don't get me wrong the Q5s is still very enjoyable but if your a pure basshead, the older Q5 with the AM3E or AM3D amp might be for you. Else the Q5s is very pleasant and musical to listen to as it just seems to do things better across the board.
Overall which do I prefer?
The Q5s with the AM3D amp.
So much so it has replaced the Q5 for all of my travels (Pre Covid-19 I was on a plane about 25% of the month) as when you have that cigar smoking crying baby in the seat next to you, a good pair of IEMs, The Q5s and great selection of high quality digital media make it all just go away and can put you in a very happy place for those hours seated in a cramp seat with nowhere to go.
For what its worth, and again IMO
Hope someone here finds this helpful or useful.