I've had two BTR5s, one stopped charging one day and Amazon took it back, the other worked perfectly for almost two years and is now rehomed
Thanks for your input buddy, appreciate itI've had two BTR5s, one stopped charging one day and Amazon took it back, the other worked perfectly for almost two years and is now rehomed
I haven't noticed sound improvements but I'm amateur on that field. BT/LDAC seems to have significantly better (longer distance inside the house) reception before cracking
My main motivation was the 4.4mm jack as I broke the 2.5mm three times
I agree the 4.4mm and feature upgrades in general were what drove me to pull the trigger without any real reviews available online. My brother has the he400se too so I'll be able to do an apples to apples comparison. Will try to give a quick update if anyone cares for it 
If you use it as a dongle dac, you'll have lossless audio (yes for that) but the btr15 through the Bluetooth connection will still require the source of the Bluetooth signal to use LDAC codec or it's still going to output AAC so you'll have the same issue as just using the xm4 over Bluetooth. If you're only looking to use it wired I would suggest a cheaper dongle dac instead as your xm4's have Bluetooth and if those are the only headphones you're going to use with it's not worth getting a btr15 in my opinion. Hope I have been of some help
LDAC is a "Bluetooth only"codec if your source doesn't support LDAC the whole set up won't use LDAC . I don't see how you would need the btr15 in this case. I feel like a dongle dac would be more appropriate as you're planning to just use the setup completely cabled. Only thing you'll get out of the btr15 is that it can use its own battery when connected to your iPhone and not drain it's battery to get power but.
I don't understand this part. If the iphone is connected with the cable to the fiio, why doesn't the fiio transmit in ldac to the headphones? iPhone bluetooth should be bypassed by the fiio since it is connected with the cable. what am I missing?
…because LDAC is a a wireless (Bluetooth) protocol. That’s its entire purpose.
LDAC is as mentioned by EdgeDC above me a protocol to transmit high sample rate audio "high resolution audio" over Bluetooth as before LDAC existed the Bluetooth audio transmission quality was not as "hi-res" but a direct connection was and still is hi-res, when you connect a btr15 or any good dongle DAC to the phone directly it bypass the need for LDAC completely as now you have a direct connection to the source and you can have it output at the highest sample rate without Bluetooth codes as you're not using Bluetooth in a wired connection. LDAC transmit 32-Bit/384kHz audio but Direct connection to a dongle DAC/ BTR15 will also output a 32-Bit/384kHz signal but without the need for LDAC. LDAC=BLUETOOTH ONLY. also LDAC not some revolutionary tech that'll make your headphones sound better so if you're doing all this to make the 1000XM4 sound wayyy better that's not going to happen, maybe some additional details in sound but they are still XM4's afterall so don't focus on LDAC that's all.
Basically you can't because the iPhone only supports hi-res audio over a wired connection which you can get with a smaller dongle DAC that support 32-Bit/384kHz (hi-res audio) but over Bluetooth with an iPhone you won't and that's that no workarounds for it. Also a btr15 Vs a cheaper dongle DAC won't show any major audible difference in sound quality or increase the volume of the headphones or anything substantial as your XM4's are active headphones and the audio processing is done inside the headphones themselves and you can't bypass that so quality of source doesn't matter that much imo but someone can correct me if I'm totally wrong here. Pretty much the BTR15 or anything like it that Bluetooth is useless to you and you should only look into a cheap dongle DAC at the most but don't expect your headphones sound quality to be drastically better either and if you aren't going to use streaming platforms like tidal/qobuzz or download/purchase HI-RES audio files (FLAC,WAV etc..) and you just use Spotify Apple music or something similar instead and don't do anything and don't even waste your money not even on a dongle DAC.
I believe you have that part correct: BTR15 is, for BT, only a receiver. But something like a Hiby R2-II can act as a BT transmitter: you connect it to your iPhone via a “smart” cable (or cable + adapter) to get lossless audio, and set it to transmit BT LDAC to your XM4…. Not sure it’s a very practical configuration though.
