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Impressions: iBasso T4

post #1 of 28
Thread Starter 
Hi guys. I got my iBasso T4 last week, I have burned it in continuously, and listened to it almost exclusively for a while (apart from when comparing it to the Mini^3). These are my impressions.

The iBasso T4

As highly anticipated, the T4 is a very small amp, which means a trade-off between size, sound quality and driving capability.
The equipment I have used to review it is composed by the iRiver E10 (mp3 player, used as line-out at full volume), the Head-Direct RE0 as high impedance IEMs, and Mini^3 as direct comparison.

Size, battery life, build quality, switches

You have probably already seen pictures of the amp elsewhere. It's very tiny and thin, which gives the advantage to use it in a jeans pocket with most mp3 players. This is how a portable/commuting amp should be, size-wise.

Battery lasts about 15+ hours to me, but I haven't counted it exactly. Other people are reporting more battery time (18 hours). The T4 allows me to use it for a couple of days of listening, after which I have to worry to charge it again.

Build quality: while it doesn't look built like a tank, like I could say for amps like the Mini^3, Corda Headsix or iQube (which I owned in the past), the switches are pretty sturdy and behave better than the previous iBasso T2.

The iBasso T4 comes with a cheap mini to mini interconnect, pouch, usb charger + wall adapter.

Other than power switch, it has a gain switch (the output is already strong at low gain, powering the RE0 to medium-to-loud volumes at 7/10 on the volume pot) and a bass boost switch (subtle).

While other people have defined the T4 as transparent, I don't think it's the area where it shines. It has a bass hump that can be especially felt in the midbass area, making the sound slightly fuller. This takes away from neutrality. The enhanced bass is felt even against the Mini^3, which is not weak in that regard, but rather punchy.
The bass doesn't only add fullness (not always welcomed), but also some tactileness to the bass (more pleasing to feel).
The midrange is pretty flat. The treble is slightly laid back, but doesn't mask details. There is some softness in the lower treble, which takes away sibilance, and makes cymbals slightly weaker. In direct comparison to the Mini^3, the Mini boosts the treble a bit, making things more exciting and detailed. The iBasso is softer, still not as opaque as the old T2 was.

I consider the Head-Direct RE0 to be neutral. They respond to amplification by gaining bass authority, and the iBasso gives more of it than the Mini^3. It isn't always noticeable. In certain tracks it's more pleasing, while other track don't like any added midbass.

The other thing for which the RE0 respond well to amplification is soundstage. Both the Mini^3 and T4 behave equally well in this regard, helping the RE0 in spacial abilities, instrument separation and soundstage size. The T4 is pretty good at instrument separation, even if not being a trebly amp. Still, the Mini^3 adds some refinement over it.


I would use the T4 with these portable headphones:
Yuin: PK2, OK3, OK2, OK1, G1
Etymotic: ER6, ER6i, ER4P, ER4S, and Apuresound recabled
I have not heard them, but going from Kostalex descriptions I'd use it with Audio Techinca CM700 too.

I wouldn't use the T4 with:
UE: Super.fi 5 Pro, Triple.fi 10 Pro
Shure: SE530
Head-Direct: RE1
Yuin: PK1
(bassy earphones)


The iBasso t4 acts as both a portable headphone amplifier, and as a "bass fullness booster". While the first statement makes it very useful with many IEMs, I think that the second statement prevents it from being an all arounder for everyone's needs. It's not neutral, and the Mini^3 is technically superior. That's also easily expectable. If you are looking for a transportable amp for office use, the T4 doesn't make sense to spend money for something this small, which brings some limitations to its sound reproduction. If you are looking for a small portable amp to power high impedance portable phones, the T4 is a reasonable choice. It's also interesting to note that almost all high impedance earphones/clip-ons have lean bass, so the T4 makes sense for them.
While not being neutral from an objective point of view, it's still useful when using it with headphones which won't suffer from its added midbass power (in stock mode: the bass boost switch adds some subtle bass, while not being very different).
Ultimately, where the T4 distinguishes itself over other amps is its size and perfect convenience. It isn't a cheapo bass booster like I found the Fiio E3 to be. The Fiio lacked both resolution and spaciality.
If one needs a commuting portable, the T4 is one of the ways to go (the other would be the Supermicro IV, if the situation with Xin gets better). Otherwise there are other interesting choices, like the Mini^3, and others that go upper in the price bracket.

post #2 of 28
Nice report. I don't get the bass emphasis you mention, though I did at first but as the unit got more hours on it I found it/find it, to be more transparent. I have used the UM2, Ult Ed. 9 and 750's and the HD650's. Oh and the PortaPros, which can be bassy but they are fine and I can't stand heavy bass.
post #3 of 28
Thread Starter 
I have about 50 hous on my unit.
post #4 of 28
Gotta agree with John now. Just noticed today that the bass hump just disappeared from my T4. My T4 has about 100 hours on it now.
post #5 of 28
Thread Starter 
Good, I'll update the review if things change.
post #6 of 28
If this is true:

I wouldn't use the T4 with:
UE: Super.fi 5 Pro, Triple.fi 10 Pro
Shure: SE530

Then that is somewhat uncool since those are very nice and good earphone. It seems weird that the T4 is made for these kind of phones but sound "bad" with the cream of the crop?

I was thinking about getting the 530´s because the Triple.fi 10 Pro are sticking out so much and i really don't like it. The Etys are hard to get here where i live for some strange reason and its really nice to be able to return something like this if they brake.

Do you think the 530´s will fit better when the amp is burned in? I have never listened to them so i don't really know.

I cant seem to think of another headphone that would be as nice.
post #7 of 28
Yeah I find it very strange that it would not sound good with the RE1s. I was planning on getting this and the RE1s, but if it a no go, I guess I will have to look elsewhere. Can anyone else comment on this synergy (or lack there of)?
post #8 of 28
I'll be able to post my opinions once my t4 arrives. I'll make my comparisons with the se530's though.
post #9 of 28
Thread Starter 
The T4 is slightly bassy, and noticeably soft in the upper end. When using it with the Super.fi 5 Pro, this means two things:
-it boosts the bass a bit more (not needed)
-it smoothens the lower treble spike of the Super.fi 5 Pro (cool, you want this)
So in the end the trade off might be worth it.

Regarding the RE1, I don't have them anyore, but I found them to be very recessed in the same lower treble region where the T4 is soft. So, "doubled softness" is not something I'd personally seek.
Soundstage and volume wise, the T4 would be enough to power the RE1 very nicely.
Soundwise, a Mini^3 with its better crispness would let the RE1 shine more.

Commercial-wise, the T4 makes sense since most earphones are sibilant, and the little amp fix ths somewhat. Anyway, since I personally ditch all headphones whose treble response produces sibilance, I usually look for neutrality in an amp.
post #10 of 28
Pics Pics Pics?
post #11 of 28
Thread Starter 
Will take some later, as I have to overcome my lazyness.
post #12 of 28
According to your (excellent I have to add...) review this might be just the thing to make the HF5s really sing.

After I burn them in and upgrade eartips to Complys I think I will seriously consider the T4.

For one it looks dead gorgeous, and it is very handy in many cases...

Let's just see...
post #13 of 28
Not recommended with UE triple.fi's!
Why would this be? I've planning on getting the T4 as both the size and price are appealing for my first amp of any kind.
post #14 of 28
Originally Posted by CENTRAL View Post
According to your (excellent I have to add...) review this might be just the thing to make the HF5s really sing.

After I burn them in and upgrade eartips to Complys I think I will seriously consider the T4.

For one it looks dead gorgeous, and it is very handy in many cases...

Let's just see...
It worked very nicely with my HF2 which is the same just with the mic added. I had to sell it however since I need it with an iPhone as source and the lack of rf shielding made it impossible to use in that configuration unless I set the iPhone in airplane mode. I will now be looking to the Pico Slim but that will be an entire different price range. For it's price I think the T4 is a little marvel if you need something ultra portable
post #15 of 28
nc8000 what were using with your T4? Inyour sig you have ER4-P's was it those?
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