This is also my philosophy.
Need 1 solid state no matter what and it has to be a good one at that. I dont think you have to spend an extreme amount as well. Variety and synergy are the key.
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Intro and TLDR
The mass kobo 428 is the kind of amp that tends to sound at least good enough with most headphones, but with those that synergyze it makes for a truly remarkable combination.
The sound presentation is generally a more intimate one, with a bit of a forward presentation, good dynamics, apart from those things it varies a ton with different headphones. Ive heard both smoother and dryier characteristics, and different tonality shifts with different hps.
It also drives tougher headphones than the numbers would suggest. Its kind of insane that a dollar bill sized portable amp running on batteries can really trade blows with the desktop amps around its price. Great for travelling and home use, not pocketable (unless you are “that” guy).
Early impressions
I played around the mass kobo a bit, I first started using it about 3 weeks ago, not like for that many hours but I would have if I could.
It actually surprised me in many ways. What it did with 470ohm aths, also the lcd3pf is hard to drive but it could deliver some good punch for a portable amp.
Oh yeah im running this on 4 batteries, it was designed for it and it shows. M0n said the PSU was optional, mostly for convenience unless you have a real good 5v one.
The two 470ohm ath worked perfectly.
The 600ohm beyer and lcd3pf did have insanely good mids and highs but the bass was not working as well enough as in like every other desktop amp I own lol
The amps signature is very unique because I find it to be more mids and specially treble focused (while relatively neutral)… but oh son theres some black magic here, if some headphones lack bass quantity the MK428 is like “here son take your bass”.
The bass sounds groovy. No worries. But if looking for big punch warm amp its not this one.
what I used
Files > Matrix xspsif 3 > Exogal upgraded comet + > mass kobo 428 (bal to bal)
I havent tested if theres a different sound SE out vs the BAL out but my guess is yes the balanced out is a bit better. Coincidentally all of the headphones I used balanced I liked the matchup more than the SE matchups. Both were great tho.
—matchups and comparisons—
ATH r70x (BAL)
So dynamic, so intimate, rich textured mids and krispy highs, great clean bass punch although it could feel backstaged in some songs depending on the records mix.
Intimate presentation and approach.
Definitely not as punchy nor as big of a stage as in a BHC but I think thats fine.
But dont worry when the bass drops the bass drops.
I mention this because I think we r70x/hd600/650 enjoyers like our punch to hit us.
ATH adx5000 (BAL)
These 2 are made for each other.
Again another intimate experience but very different from the r70x.
The beauty throughout the whole frequency spectrum is just special. Thats around 40hz to 20khz.
To me the timbre is as good as it can be for female vocals, some strings, most wind instruments and some piano. Works for a good variety of genres but Id say regular jazz and fusion and vocal jazz is what I liked these the most for.
The technical capabilities (in this match) are also impressive, quite easily rivaling amps from 1k to 2k new, I havent heard that many (5 or 6?) but the MK428 would be my pick for the adx5000.
The frequency response is a nice neutral bright one (The adx5000 like to get bright sometimes but here its controlled and the bass is very satisfying).
Random note: These headphones are not suited for hip hop.
ATH AWAS (BAL)
The AWAS are closed yet they sound bigger than the r70x and adx5000 lol; now we are going for this a little bit of warmth yet slightly brighter tuning that works well for most genres.
Quite fast transcients for a closed back dynamic I must say, the texture is also very physical. Id say maybe one weakness is the depth is not very deep.
Compared to the burson soloist 3xp, audio technica bha100, the yamamoto ha02 and the pass labs hpa1; the MK428 goes for a more fun midforward tuning thats a bit brighter than those 4.
Great very fun combo and quite generalist with a bit of everything, very easy to like; yet the treble and forward mids may get hot for some with this amp.
AKG k812 pro (SE)
SE sounding good on these rather demanding akgs.
The microdetails and instrument separation stand out at first. im enjoying this combo, the “more balanced approach” the MK428 gives to these akgs frequency response really tames the highs and evens out the midrange for a more “generalist” sound, compared to lets say a reference sounding amp.
Reminds me of the akg k702, more studio like signature but still with the akg sheen and forwardness.
I dont find problems with any genre or instrument in particular with this combo, with other amps its usually more striking , more macrodynamic and specialized with its large stage yet forward presentation; but here its just smooth.
Again a more intimate experience even with the k812. Its closer to a medium sized stage here.
Grado RS1e (SE)
Amazing for electric guitars, keyboard, vocals and to a lesser extent drums and bass.
Gotta give it to the vocals again, they sound amazing, this combo gets the vocal timbre so right for me, so organic.
Also the macrodynamics are actually quite something with this pairing. I think these grado are getting a bit more help in the macro section than other headphones.
I also guess thats whats helping the electric guitars sound so alive.
The staging and instrument separation is rather average, not gonna lie, nothing special here lol.
Still very nice smooth combo, specially for a grado, if you were looking for a grado but the forward mids or treble were a bit too much, the rs1e keep the original grado sound while making it less aggresive.
These rs1e are soft here, but also on most tube amps. I find the yamamoto ha02 to get the separation and staging better but I also do really enjoy the slightly more midforward mass kobo.
Grado RS1 with ps1000e drivers (BAL)
What are these
Vintage RS1 arrived 90% dead when I got them but I was on denial so I didnt return them I thought I could fix them, drivers got replaced by ps1000e’s, they sound great now.
I think this sounds like the child of a ps1000e and a rs1i but closer to rs sound.
These ones sound crispy, as in magnetic record and vinyl filters/samples sound more like the real thing. They pop out.
The side consequence is some hiss or noises are also augmented which can be bad or good depending wether u listen to shoegaze/noise music or not
Vocals, piano, strings, air instruments, distorsions, guitars, everything lol sounds good. These are my favorite grados so I dont have anything bad to say about them and specially with this matchup that sounds more lively than my other amps. (For these I have used ath bha100 the most and yamamoto ha02 also)
Lead instruments and/or vocals take center stage while the others go to the sides kind of presentation.
Some records that are compressed (by design or not, often as a filter) sound more compressed, and these headphones can also sound congested if theres way too much going on; but they seldom miss for my music, no exception so far with the mass kobo either.
I also tested the grado sr325i gold (SE) and the ath ap2000ti (BAL) before writing the impressions and they match up real good, they would be on the half or upper half of the better matchups here if I had written their impressions.
and yeah sorry for the brand variety LOL.
Conclusion
Seriously unexpectedly good, most of my stuff is easier to drive and this thing literally sounds good with everything not super power hungry and even with those it spits out something acceptable to listen to lol
Sorry if you have never heard any of these headphones and amps lol, its what I like Its what I listen to.
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Doing some impressions of the Mass Kobo 394II
Chain: PC > Alpha USB > Mojo Audio Mystique EVO Pro '21 > MK 394II > mostly HD800s
*unfortunately setting up this amp somehow restarted my AES issue, so I had to use a cheap BNC to RCA spdif cable I had lying around
- Control and Grip- excellent. This amp really does well here and nothing seems to bleed into each other. Really standout for me
- Impact and slam- excellent. I am feeling more of that deep rumble in some ways like you would at a venue physically feeling the air waves
- Speed and separation- excellent. Very speedy and separates things pretty impressively too
- Bass texture- excellent. I can pick out the differences between bass notes where I couldn’t before. They are nuanced and specific to themselves
- Overall dynamics- excellent. I think my dac pairing helps out with more of a macro focus but the amp has no problem keeping up with dynamic tracks
- Overall clarity- excellent. Seeing some of the impressions on this forum discussing the subtle sweetness of the 394II are accurate. Just enough not to be too analytical
- Background Blackness- excellent. No real noise, and coming from a tube amp that was sensitive to external interference this a drastic change for me. Others may not have that degree of change fyi
- Timbre- excellent. I think this is something that I find a standout. The 394II is an honest amplifier but has a certain magic with all the tracks I’ve payed. We will see how it goes as time passes tho lol
- Tonal density- excellent. Notes and instruments feel weighty and packed with information.
Vocals- excellent. A lot of space around the artists vocals - Macro/Microdynamics- great. I think my pairing has a macro focus but am not losing much micro detail info
- Resolution- great. Really revealing, I could pick out echo’s and room content on some tracks that I hadn’t before
- Placement accuracy- great. Headphone dependent but overall placement conveyed seems coherent
- Presentation- great. Pretty organic and realistic
- Extension- good. Vocals are articulate and still refined. Same thing here with bass
- Stage size and overall space- good. See my comment on forwardness. Stage doesn’t seem compressed enough to be messy, just forward
- Forwardness= my dac > amp combo seems fairly forward in nature. Pretty close in the presentation but things are not messy and separation is fine
I continue editing these notes over and over again as I go, but I wanted to at least get something out for the time being
I think this amp just does a nice job in most things including different genres and headphones. Its an honest voicing but really enjoyable if you want a no nonsense solution. I will say things like the VC are a bit sterile and unexciting but still rather technical, just not what I’ll be grabbing if I am on the 394II
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This is probably just a bit desperate try but since Mass Kobo 394II is discontinued now I would like to ask here in community to keep me in mind if someone will be selling and is willing to ship in Europe.
I had this amp as my upgrade wish eventually but failed to anticipate it will be discontinued so soon.
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According to some rumors there’s going to be a newer version late this year so don’t lose hope on your upgrade!
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That would be actually great also from timing perspective. Thanks for heads up!
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Going by the price it might be the 394 successor
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thats exciting. Im really enjoying my 433
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So this is what my endgame amp will look like
SICK 
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