Bluetooth Adapter and Wireless Audio Receiver with Microphone and 2.5mm Jack for Sennheiser HD598 / HD598Cs / HD598SE / HD595 / HD599 / HD559 / HD569 / HD579 / HD518 / HD558 Headphones

For all the marketing on this store page that the product is specifically designed for the HD598, it doesn't fit! And I have no clue if I received the correct model (SEHD). There's no model code on the device itself, and the packaging suggests i received the wrong version. The 2.5mm end of the cable that comes with the headphones has two grooves on the side. This is to assist with keeping the cable locked to the headphones. In my photos where i hold the airflex next to the 2.5mm cable, you can see that the airflex has about the same diameter as the 2.5mm cable but doesn't have the grooves, so it won't snap into place. Connecting the device to my phone via bluetooth was very easy. Just a shame i could not hear anything because i can't plug the device into my headphones!

This deserves more praise - works with my HD 598 flawlessly, and working perfectly as described. 1) I just received it so I cannot comment on the battery life yet 2) So far the audio quality is excellent, identical to that of connections with cables. 3) There is not a delay as obvious as your typical bluetooth speakers, and I can almost say that latency would not be an issue even for games - I'll test it out myself 4) The proprietary plug was a non-issue as they have dealt with that in their design already, it fixes itself into my HD 598 without any issue 5) For those who suffered terrible sound quality, disable your mic (voice input) from the bluetooth connection (AF Lossless Hands-Free AG Audio output), as well as limiting the output to only the AF Lossless Stereo. The terrible audio comes from the "AF Lossless Hands-Free AG Audio output", and it is a common thing for bluetooth audio devices, not a device-specific issue.

I purchased this adapter hoping to turn a pair of Sennheiser HD560S headphones into wireless ones. Although this specific model of headphones isn't one listed, I thought I would take a chance and see if it would fit. At first this wasn't the case; however after some fiddling around, I managed to get it to work. The problem is that it wasn't easy to seat the connector in a headphone jack normally occupied by the proprietary Sennheiser cable. Initially I was only able to hear sound in the right channel. However, having gotten it to connect, I am very pleased with the sound quality of my HD560Ss operating wirelessly. I think the codec shared by the adapter and my laptop is of low quality - probably SBC - but owing to the quality of the headphones the sound seem to leave little to be desired. I would recommend anyone buying this adapter to not despair if initially it doesn't seem to work.

The connection drops for about a second ever 2 - 3 minutes. I also can't keep a connection to these unless I'm in the same room as my phone. I can easily be 4x the distance and keep a reliable connection with other cheap bluetooth headphones. With the dropped/freezing issue, it got bad enough that I restarted my phone, restarted this little thing, and then started counting off how often it happens. This was with my phone being 3 feet away from the headphones, Sennheiser DC 599s. This issue does not occur when I have the headphones corded. This issue does not occur with other, cheapo $20 bluetooth headphones connected to the phone. Through this process of elimination, combined with being ale to tick off dozens of times it dropped / froze for a second over two different 1 hour listening sessions on two separate days, I am convinced that the issue is with this product.

I took one for the team and it didn’t disappoint! I was extremely nervous to buy these at first since there were no reviews for my exact model of headphones- Sennheiser HD599 ‘s. Then, after seeing some of the passionately negative reviews… it admittedly took me a while (and all of my other headphones breaking) to finally purchase these and give them a try. My main complaint is how I wish I got them sooner! I was worried about the adapter not fitting like some of the other reviews stated, but it fits perfectly in the HD599’s. The audio quality is just as good as wired headphones. I immediately noticed a very cool feature- if you have an iPhone, this adapter is immediately compatible with your widgets without doing any extra work! You just have to add the built in “Bluetooth Headphones” widget to your Lock Screen or Home Page, and it will show you the exact amount of charge they have as long as they’re connected! I am unsure about how to set that up with Androids, but I’m assuming there’s likely a similar feature since it runs off of Bluetooth connectivity, not iOS. My only minor “complaint” is that it speaks the words “Power On”, “Power Off”, and “Low Battery” to you in a robotic voice as it’s built in power indicator, like cheap speakers do. However, it is nice to have some sort of power confirmation that doesn’t require checking my phone when I’m not on it, and it’s definitely better than nothing. Overall, they do exactly what I wanted them to- I didn’t have to troubleshoot or mess with any of my settings to get them to work like some reviews stated… mine just plug, play, and go. It’s very nice not getting tangled in the oversized amp wire that they come with anymore when I want to use them for things like casual listening, handheld gaming, or work tasks. This adapter grants me free range of motion so I can wear them comfortably while doing activities, without providing me with a dip in audio quality. Fulfills the exact purpose I got them for and provides the quality I was looking for.

Battery life sucks worked ok for the first day and now on the second it literally keeps crashing my pc when I connect it to Bluetooth..... literally testing my computer with 2 other Bluetooth headphones no issues ..... I connect this thing now and I get anywhere between 2 min to 30 min b4 my computer just hard locks it self....... also the mic quality is absolute trash if u try to make a call this stupid pos isn't even glued together properly and this is what happened to it after i wasted 2 hours of my life ripping my pc apart thinking the ram died

Update: turns out the range and connection stability leave much to be desired. And probably the audio quality, considering this is for people who own Sennheiser wired headphones. So I hope they will improve this product's innards because the concept really fulfills a need. I wanted a product like this for a long time because great headphones should last a very long time, but bluetooth tech gets outdated and lithium ion batteries wear out. This lets use your favorite headphones through several generations of bluetooth tech. This unit sounds great and connects easily to my Android device and my Apple Watch. I haven't tested range. It remembers multiple devices, but I haven't tested simulaneous connection. The form factor is pretty much perfect for not hitting you in the shoulder but also positioning the mic well. No complaints about voice pickup or quality from people on phone calls. The only thing I've identified that would improve it would be USB-C charging. I had nearly eliminated all micro USB from my setup, but oh well. I decided not to take off a star for that, but it's a little unfortunate.

Like a fool, I got myself a Sennheiser HD599SE under the mistaken belief that it had its own built in Bluetooth. When I realized that was not the case, I decided to take my chances on this receiver despite the less than stellar reviews. I wasn’t disappointed. The receiver works great! The battery life is the only thing I wish was better, but as long as you remember to charge it each night, it shouldn’t be much of an issue.