The BA5 is another one of TRN's excellent-sounding and superbly built pairs earphones in the upper-budget range of this project ($40~$50), only this time we're dealing with BA-only internals, 5 BAs per channel, to be more precise.
The resulting product sounds about as I expected: the BA5 take a few steps back when it comes to bass in favor of a more mid-centric experience. The bass is still there, at least when it comes to mid-bass, but it's dryer and less exciting that what you would hear using one of the dynamic driver-inclusive pairs from TRN, like the V90. The mids and highs, however, do an excellent job at reproducing vocals and instruments and throwing them right in front of you without being too intrusive.
While I wouldn't pick these for bass-oriented music styles, if you mainly listen to vocal-oriented music styles, then I highly recommend giving these a try.
NOTE: My pair comes from an early batch, which had an issue that is quite common with BA-based earphones: occasionally, the sound would fade gradually until nothing can be heard from one (or both) channels. Usually, putting some air pressure (like suckling on the nozzle shortly) restores the sound for a while, only to fade later again. This is, allegedly, a humidity-related issue and should be solved on newer batches, so I didn't include any further discussion about that in this review, but still worth mentioning.
As always, TRN knows how to design comfortable earphones. The shape of the BA5 is quite common, it's ergonomically shaped to sit snuggly inside one's ears, and the lack of sharp edges ensures no skin irritation. Do take in mind that these housings are substantially bulkier than the ones on V90, so users with smaller ears could find them too just big. I couldn't pinpoint any comfort issues that are worth mentioning, but using better wide-bore tips is much recommended, and as always, I recommend the ear tips that come included with ROCK Zircon.
Lows / Bass
The bass is very clean and the punch is there, but it's rather on the dry side. For the lack of a dynamic driver, I would assume, the bass is enough for warming vocals and instruments, but can be underwhelming when some oomph and depth is needed, like with electronic music. Using a weak source, the bass struggles to keep up with deep bass content, leaving the mids and highs to dominate the sound to an uncomfortable level on higher volumes. While not designed for electronic music in mind necessarily, the bass sounds mild, comforting and stable if you mainly want to enjoy some vocals and/or instruments on a moderate volume level.
Mids / Vocals
The mids on these earphones excel at precision and detail, and are upfront on a rather comfortable level, unless volume is excessively bumped. The mild bass fills the vocals with enough warmth to keep vocals interesting and authentic, without much colorization besides what you would expect from balanced armatures. These kind of mids can also be great for competitive gaming, as it reveals the most subtle and distant sounds, like footsteps. Shortly put, I've got nothing to complain here.
Highs / Treble
Like the mids, the highs are also crisp and detailed, and not exaggerated like with many V-shaped earphones (but that still depends on which ear tips you use). Depending on the ear tips, volume level and recording quality, the upper-mids and highs can still produce some sibilance or uncomfortable sharpness, which can usually be remedied by reducing the volume. It's a common issue that isn't worth fussing about, not a deal-breaker, but still worth of improvement in the future.