So far I've tried or owned a few all BA sets. I usually use them for stage monitoring as the all BA sets tend to have very good isolation (usually they ain't vented cause they don't have DD) and they also generally have better technical performance over the single DD sets.
My main beef with these pure BA sets is that majority of them have BA bass, which generally means lesser subbass extension and less bass movement of air. So the bass sounds a bit unnatural coming from a DD bass. On the flip side, the BA bass tends to be faster than DD bass, so a few metalhead friends of mine like BA bass for the speed and accuracy. I don't listen to metal, so can't verify this. Another area that I don't really like in pure BA sets is that BA timbre is present for acoustic instruments compared to single DD sets.
As they say, different strokes for different folks, and of course exceptions do exist for the above.
Stuff I've tried/owned (in alphabetical order):
Acoustic Effect TRY-01 (1 BA) ($149 USD). Japanese niche brand. Neutral set, bullet shaped and comfortable. Very good timbre for a pure BA set, lacks subbass as expected for a 1 BA set. Organic timbre, good soundstage and technicalities. Very smooth and fatigue free, no sibilance. Very good for acoustic, classical and jazz. Unfortunately, cable is not detachable, and due to the lack of bass, not gonna be an all rounder (eg doesn't fare well for EDM and other bass forward genres).
Audiosense DT200 (2 BA) ($149 USD). Warm neutralish set, good tonality, very smooth and dark treble. Non fatiguing. Great fit and isolation. Typical subbass roll off in BA bass. Technicalities and soundstage not the best, probably due to the limitation of 2 BA.
Audiosense T800 is a 8 knowles BA set. $298 USD. Mild V shaped, excellent technicalities and 30 dB isolation. My go to for transit and stage monitoring, though it is bright, so not the best for treble sensitive folk, unless u wanna play with tips, sources, knowles filters. It has a vented subwoofer BA that makes it sound like a DD bass, so very atypical for BA bass. It is my daily beater set too, but it is a bit picky with sources as it fares better with stuff that has the lowest possible output impedance.
Hisenior B5+ is a 5 BA knowles set at a rather affordable $70ish USD. Above average technical performance, midcentric set (which is rather rare tuning wise). Midcentric sets are pretty niche, it is not all rounder due to the tuning (lacks subbass extension and treble extension but it is good for vocals/acoustic stuff). Soundstage is below average but isolation is good. My backup set for stage monitoring.
QDC Anole VX (10 BA) ($2ish K depending on CIEM or universal). The big kahuna, my end game all BA set. Excellent technicalities, good tonality. Has tuning switches to change the sound signature too. BA timbre unfortunately. And also unfortunately I have an emotional attachment to my kidneys, can't sell the kidneys to fund this set in my lifetime.
TRN BA8 is a 8 BA set, just released, very shouty in the upper mids/lower treble for me, despite the good technicalities. Supposed to be a successor of the TRN BA5. They launched the BA8 at $140 USD, I think it dropped a bit to $130 after the initial reception wasn't the best. Amazingly, for a $130ish flagship, the accessories are almost the same as a usual $30 USD TRN budget set (ie crap cable and a few tips). But to distinguish this flagship set, TRN graciously added a $3 metal round hard case (yes it is 3 bucks on Aliexpress). At $130 it is a hard pass, u can get some gems like the Fiio FH3, TRI I3, some ThieAudio stuff at that price, and I think only trebleheads will like it.
Westone W30 (3 BA) ($400 USD). Warm neutralish set. Good isolation and fit, technicalities above average. Wouldn't recommend it as the Audiosense DT200 at less than 50% the price can meet the same sound quality.
Westone 3 (3 BA) (no more on sale, was going at $300ish USD previously). V shaped. Good isolation and fit. Non detachable cable. Midbass bleed present, and can get hot in upper mids. I find it is similar to the KZ ZS10 Pro, but at 10 times the price.
Westone UM1 (1 BA) ($99 USD). Neutralish, no subbass. Above average technical performance.
