I just recently had a series of pm asking me to compare the PX and B400 and I added the IT01 to the mix. I've grabbed the relevant bit from the exchange and it follows. The comparison was specifically about mids and treble for classical music and violins so it isn't a complete comparison but one with a specific area of concentration.
Saw you own both PX and B400?
Can you share your thoughts on how they compare? I'm wondering how the mids and treble work for things like classical music and violins.
Yes I own both. Initially I was very underwhelmed with the PX. I later purchased the B400. I've been mostly dealing with the more inexpensive Chi-Fi market (<$100) and have been spoiled by the hybrid designs that combine the bass and sub bass from the dynamic driver with the tonality of the balanced armature driver(s). So I found the B400 to be way too weak as far as bass response. Add in a bit more time, some other IEMs and listening to the different types. Finish with a Burson opamp I received a review sample of that is making me go back and re-listen to other IEMs so I can get a good feel for exactly what the opamp does to the sound. So when I went back to re-listen to IEMs I hadn't for a month or longer I found that I liked the PX and really liked the B400. So as just a not well thought out just off the top of my head opinion I'd say either would be OK for what you're looking for. Both have smooth and polite treble versus the shrill extended type that's typical, especially of Chi-Fi hybrids, of the fun, consumer oriented V or U shaped tuning. I'd describe either as good for listening to performances versus those fun tuned ones which are nice for playing music if you understand what I'm trying to describe.
… I have this new to me CD I just ripped to flac yesterday of a recording by the Philharmonia Baroque Orchestra with period instruments of Handel's Water Music I've been wanting to listen to. So I will. And I'll specifically swap between the PX and B400 and let you know what I hear.
My primary source for the comparison is: Water Musick, George Frideric Handel, Nicholas McGegan (Performer), Philharmonia Baroque Orchestra
Secondary: Clemencic & His Flutes, Rene Clemencic. I own both on vinyl and purchased CD copies. Both on the Harmonia Mundi label. CD ripped to 16/44 flac. Both horribly multi miked but at least unlike major labels at the time didn't have the microphone shoved inside the instrument (or at least a bunch of recordings from then sound that way) so each instrument or group of instruments have their own sense of air and placement in space. But the mixing without concern for physical placement ruins any possibility of getting an aural image of the performance. It just isn't possible to talk soundstage with these recordings. These are both recordings using period instruments so natural horns versus French horns and trombones. Strings with a more mellow edge than modern instruments. Wooden woodwinds as opposed to metal flutes and piccolos. Even more unusual with the Baroque Clemencic music choices.
The primary reason for the comparison is to decide which if any would be good for listening to classical music and especially strings and more especially voilins.
I could call this piece "A tale of 3 linear IEMs" and not be too far wrong. The iBasso IT01, Massdrop Mee Pinnacle PX and Brainwavz B400. I was initially thinking of 3 flat IEMs instead but the IT01 isn't flat but my mind was thinking absent the more typical consumer frequency response with boosted and reduced responses. The IT01 is linear but is tilted with a bass and sub bass extension that lessens throughout the midrange until it is truly flat through the treble range. Both the PX and B400 are tuned to have a flat linear response. I used my Shanling M1 as a transport for my Xduoo XD-05 which has a Burson V5i opamp installed.
The PX are the least efficient of the group needing additional volume to get the same sound levels and the IT01 the least but all. None required me to select the high gain setting on the M1 so I think all 3 can be driven sufficiently by whatever source you use.
I could make this very short and say that they all sound the same and I wouldn't be completely wrong. But there are differences. In fact once I realized one I could go back and listen again to music I'd already listened to and I could identify that difference there but to a lesser degree. So by the time I was done I listed to short segments of the same music and could assure myself that any given difference was there to hear.
The PX has the most 'boring' sound of the group. It doesn't really do anything wrong. It reproduces the music its given and does it consistently. It neither adds things not there nor takes anything away. It provides the least sense of bass oomph or bump but then there really isn't amazing thumping bass in the music choices I was listening to. Similarly my music doesn't have atmospheric piercing highs and the PX never got shrill nor fatiguing. The upper bass and entire midrange is reproduced well. Instruments sound like what they are. You can tell there are voilins and larger bodied strings playing at the same time. But you can hear that they're different instruments and there isn't just a mush of strings but instead there are small ones and mid sized ones and large ones. You can hear the bodies of the large woodwinds. You can hear the odd Baroque percussion. You can hear that any given instrument or grouping that was mic'd together played in a physical space. You get a sense of the walls, floor and even the shuffling of feet on the floor of the musicians not currently playing. Frustratingly you can't get any sense of the whole ensemble playing in that same space but that the recording engineer's responsibility not the IEM. You want to hear what your music sounds like and these will let you do just that.
The B400 sound very similar yet very different. The Balanced Armature design makes each instrument (or group recorded with the same mic) have its own sense of presence. I mean sonically not spatially. Everything just sounds unique for lack of a better term. But I don't want to give the impression that this means that when the entire ensemble is playing that there isn't a sense of a group but just individuals. Visually I'd describe it by saying that you could see the individuals but that you could still clearly see they are in a group. This difference in perception provided is what I think is the biggest sonic difference between dynamic drivers and balanced drivers. There isn't so much bass in my music choices that there is too much of a chance of the bass effecting the midrange and I never felt that occurring. The Baroque percussion had an amazing amount of uniqueness in the sonic sense. You could hear the movement of a hand or striker across a membrane or instrument body. Similarly the strings had a separate unique yet part of the whole reproduction that was the best of the group. The choice of all BA drivers might be of concern for bass reproduction but there was no deficiency to hear with the B400. Again my music selection only had a string bass, bassoon and Baroque percussion providing a need for low bass and sub bass.
I decided to add the IT01 to the comparison because it has a reasonably linear response and is only a few dollars less expensive than the PX. And it has the biggest sub bass and bass of the group in terms of potential and tuning with its elevated low end response. I was curious how much it might change the sound of the bass providing instruments I mentioned above. One thing that surprised me was just how much more body the horns had with these. I tend to think of brass as being in a slightly higher register than they are in this music. And I think I'd be correct if I was talking about a modern trumpet. But even a modern French horn, the sibling of the horns in this recording, has plenty of lower frequency sound. Bodies of all sorts of instruments, horns, Baroque percussion, big strings and big woodwinds, all sounded fuller. There just was more of a sense of a physical thing producing the sound versus just magic creating the sound compared to the others. Instrument groupings are still distinct as with the PX but not at the level from the B400. There were times when I was just about to think that the elevated bass was effecting the midrange and changing what an instrument sounded like but it never happened. The loudness of the passage or choice of instruments would change right before it would happen. I'm not sure if a fuller classical music selection like a full 100+ instrument orchestral symphony would produce the effect. The increased bass and lower midrange added to each instrument grouping's sense of a physical location and made the production sound more frustrating than the others. This provided the most fun sound of the group but still managed to be mostly behaved. Some instruments including strings had a slightly larger than life quality. Fun as I mentioned. Yet still obviously what they were supposed to be.
So to answer the question: does either the PX or B400 have enough of a reduced or colored upper midrange and high end make instruments particularly violins sound thin or just generally wrong?
The answer is no that they both sound good and either would be an acceptable choice. Both do a good job of reproducing the music they're given without adding or changing it. Even the IT01 which I added to the mix to see if more bass and lower mids would reveal a shortcoming in either of the comparison IEMs didn't show any such issue. In fact it did better than I expected because of its more fun tuning but the linear frequency response kept it in the pack. And it might be a better choice if you'll additionally listen to rock, EDM and other categories that want extra bass and sub bass.
