The MX3S was favoured for a nicer sound than the MX5 when that launched, it's also cheaper and has some USPs such as proper tone controls and source volume memory as well as gain memory for an output.
I would recommend the Topping MX3S for this sort of use case, the only time it won't be suitable is for very sensitive headphones like planars as it trips the protection mode. Otherwise it will power any speaker out there, as well as the vast majority of headphones, and has an incredible sound out of the box. The only reason I sold mine was because of my planars being so sensitive on it and the idea of R2R sound for under £150 was too compelling.
MX3S is also old now though, Topping, SMSL and others have newer models out, but they also cost more. Fosi ZA series are good, but they have analogue volume pots which don't play well with low volume use as you get channel imbalance until the volume is raised some more - This was what I found with the Fosi I bought recently as returned. So more me an amp or DAC has to have a proper ratcheted volume pot that is digital.
He's going on in that review saying measurements matter, but he doesn't have any. So he has no evidence?
There is this rolling debate on forums like ASR where one pocket bandy up throwing around measurement this and measurement that like it's the gospel on sound, meanwhile a smaller pocket prefer to actually use their ears and decide what sound better.
Case in point, most recently a debate regarding OpAmp rolling started with the usual paper pushers stating there is zero difference in changing OpAmps because one veteran member compared 2 OpAmps on a specific Chinese DAC and found basically no measurable difference, and because the graphs said so, it was taken as gospel, even though others have stated that you can literally hear differences in soundstage and stereo imaging, these may not always translate into a graph like frequency response does, but the pushers don't care about that,m because graphs matter,
MAN.
As you can probably guess, I side with the actual ear-enjoyers, since my experience of OpAmp rolling dates back a literal decades and beyond, back when the Xonar Essence STX was the hot topic and we were swapping in Burr Brown OpAmps to get that old skool airy sound. Fast forward to the p[resent and the same still applies, the A80's stock NE55532P OpAmps are good for the masses, but for a mere £15 or less, the OPA627 offers wider soundstage and a more music top end - That's simply not placebo like those ASR members seem to claim, I swapped back and forth multiple times on these Comete speakers and can hear the soundstage become more narrower with one pair of OpAmps, and then wider with another.
And this is why I don't really pay any mind to people who push the whole "but measurements!!!" argument.
There may well be some DACs or amps that don't implement OpAmp staging quite as effectively as others, and in those devices sure, the difference is not worth the effort most likely, but in amps like these where the OpAmp is at the literal output stage, it makes a noticeable difference.
Also you can get room shaking sound from just 10 watts, it's the quality of those watts that matter most not the actual number. Loads of youtube videos showing what just 1 watt per channel sounds like, well worth taking a see what quality is like over quantity. I recall the cheap audio man doing this very test a while ago.