It was my understanding the btr3 had 64 step volume control while the newer btr3k has 32 step volume; this is for me is a disspointment.

I am terribly sorry as this is my mistake.
BTR3K and BTR5 are 60 steps and BTR3 is 32 steps.
I am correcting it.
Please refer here
https://www.head-fi.org/threads/fii...h-fidelity-bluetooth-amp.928317/post-15535149

Thanks for pointing it.

Considering entering into world of bluetooth dac/amp.

Is there a sound quality improvement using my sub-$50 chifi IEMs with BTR3K versus plugging IEM directly into my smartphone (S10+ Exynos)?

To tell you the truth it doesn't worth it for cheap chifi iems as S10+ phone out is already good.
First upgrade to a better iem with a balanced cable and then yes the BTR3K will be a leap in performance.

Thanks Ichos. Appreciate the reply.

I'm thinking about pairing one of these, or perhaps the BTR5, with a new pair of IEMs (which I haven't bought yet, either the Fearless S8F, the ThieAudio Legacy 9, or the FiiO FH7). I know that powering any of those IEMs wont be an issue...I'm just trying to use the BTR to improve sound quality vs direct plugging into my iphone and for easier connectivity (so I don't need to mess with the headphone to lightning dongle). I was already planning on spending $150 on the Audiolab M-DAC nano until I saw that nobody on head-fi seems to have written about it and everyone loves the BTRs, so I wouldn't mind spending the money on the BTR5. But I do prefer the size factor of the BTR3k. Is the sound significantly better with the BTR5 that it's worth being a little less portable?

And, as someone who's never owned balanced headphones, should I try and get these headphones as balanced? What does that even exactly do? haha. I love good IEMs (have had my FLC8s for a couple years now) but I am far from really understanding hi-fi gear. Thanks!

Hi , both BTR3 and BTR5 sound slightly better from the balanced out as they are designed fully balanced.
So it is better to invest in a balanced iem.
BTR5 is better especially in technical performance but not by a that great margin so in my opinion judge first from a form factor view.
If you don't mind bigger then yes go for the BTR5.

I agree with Ichos about balanced cables; I let my ears decide and there is a noticeable differnce.

BTR5 sounds noticeably better out of the balanced. So much so I only use my SE846/K10U out of it via balanced. Some devices have hardly any difference SE vs balanced but the BTR5 certainly does, I had the previous BTR3 and BTR5 is a big improvement in SQ over that, but not heard this new BTR3.

If you want to decide which output is better on the BTR3K just check my latest review (Hungarian language but use Google Translate and the conclusion comparison table I put in English as well). I compared the Fiio BTR3K with my Ibasso DC01 cable audio adapter, my Hiby W5 Bluetooth player, my iFi ZEN DAC desktop DAC/headphones amp, and naturally with the original BTR3 which was a revelation in 2018. I used my Meze 99 Classics headphones for the review but also tried the BTR3K with my KZ ZSX hibrid ChiFI IEM.
What I state in this review:
The BTR3K's performance listened to with my Meze 99 Classics headphones with the latest and greatest balanced Meze cable from the balanced output came very close to the sound can be heard using the BTR3K connected with my Vorzüge VorZAMP Pure II+ high end portable amplifier (was 520€) with an asymmetric cable!!!! Digital music devices' improvement over the last three years can be described as a miracle!

Yes indeed.
I have stated that many times in my reviews.
The progress is amazing.
Full desktop devices may become obsolete!