I have a Sennheiser HD-202 which I absolutely love and will not trade it for anything else. The headphone was busted once (lost the sound in the right side) due to the wires tangling up, but lots of thanks to my awesome brother in law it was fixed and working really well.
However, with the purchase of iPhone 7 I had to face with the fact that I can't use my beloved headphone since iPhone 7 doesn't have any audio jack (Boo!)
So what to do if you're a poor soul like me? Yep, as expected, I started looking for bluetooth Audio Receivers so that I could actually use it with the new phone.
At first, I've bought a cheap ~RM 15 bluetooth receiver at. And it SUCKS. BALLS. There are humming sounds everywhere, probably due to signal leaks because they don't even protect the internal wires (just like the cheapo RM 3 USB cables). Don't buy them, even if they look very tempting. Seriously. Don't even bother. You'll just waste your money. Feel free to try them yourself if you aren't convinced. No refunds.
So, what I have ended up with is the Xiao Mi Bluetooth Receiver. It's pretty much one of the few available here that has an actual brand backing it, and is the cheapest available here, at around RM 70-80 (sob) I believe, which I've bought from a Mi shop. The storekeepers even allowed me to test it first (thank you!). And I'm sold immediately.
Alright, so first things first. Yep, it works. No humming sounds. Everything just works seamlessly. Turn on the bluetooth on your phone. Turn on the Xiao Mi bluetooth receiver. Pair it. Then boom, it works. And nope, no humming sound. Everything works just like as if you have plugged in an audio jack. So, if you're just looking for something that works, Xiao Mi Bluetooth Receiver is for you.
Next thing would be the battery life. And as per listed, it's approximately 4 hours long with full on audio listening and it pretty much aligns with my experience. Is 4 hours enough? It's enough for lots of cases, but you'd still want to bring a powerbank with you if you are in a long drive. Don't worry, that's 4 hours of listening. Just like any good Bluetooth receivers, the receiver will turn off (or was it sleep mode?) after a period of time if it doesn't detect any music. So, really, 4 hours of listening is plenty of listening.
How about the audio quality? Now, I'm no audiophile so I didn't exactly noticed much differences between bluetooth and audio jack. Maybe the bass suffered a bit (very tiny bit), but really, it is 'good enough' for me. Guess I'm a filthy casual lol. You might want to do an audio check on youtube (though I guess the quality still would be degraded due to the compression as well) or just test it yourself since the storekeepers allow testing. But definitely there's no stupid humming sounds due to cheap engineering.
The listed distance is 10 meters, and that pretty much aligns with my experience too. And the pen-like shape looks awesome and fits in my pockets without it feeling any heavier.
So, looking to upgrade your wired headphone to wireless? Just get Xiao Mi Bluetooth Receiver. Don't waste your money and time on cheap knock-offs. It's good. It works. Yeah, I unless you're from a western nation, it's pretty pricey (at RM70-80), BUT it is totally worth your money. If you've bought a headphone at RM 150, then think of it as getting a new wireless headphone at RM230, rather than getting a crazy RM1089 wireless headphone instead.