Until recently, I can't think of anyone who would use BT for any application where the signal needed to travel more than 10'-20' because, well, it usually didn't. One of my reps let me test a Mass Fidelity BT receiver that retailed for $299 at the time (~6 years ago) and the one I just saw online is priced at $249. I was using a Denon AVR at the time which worked with Airplay, so I streamed from my iPhone (I never use MP3) to the AVR and to the BT receiver. Not only did the BT receiver sound worse, the signal dropped when I was about 20' away, outside of my garage when the receiver was inside and separated by sheathing and vinyl siding. I. Was. Not. Impressed. I called the company to ask about increasing the range and they couldn't even tell me that SMA cables were easily available online. Meh.
Fast forward to September of this year, when I was in the process of upgrading the audio system at a school gym. I had originally recommended that a HEOS be used since it has more inputs/outputs than Sonos but since the school has a network administrator who didn't want to allow any settings to be changed to allow multicast and the sad fact that the people who would be using it weren't techy enough to load an app, sign in and remember to sign out when they weren't the one sending music to the device, we needed to find something easier to operate that would still communicate with the receiver over more than 100', through three concrete block walls and with a room filled with bags of water (people). The gym teacher overheard us and said that his little Ion Tailgater amplifier uses BT and he can send music over 100', which I didn't believe because almost nobody in the custom end uses or cares about things that don't use WiFi. Then, I saw it in action and I left to find out how this was possible.
Well, it seems that in the last few years, BT has undergone a big transformation and it now covers a much larger distance. I got back at 11AM, read about the changes, looked online for something that might work and ordered it around 11:30AM and it was at my door around 7:30 that evening (thanks, Amazon). I connected it to the stereo in my garage, started the music on my iPhone, started walking and expected it to cut out around 20', but it didn't. I kept walking and it continued to play. I reached the end of my 100' driveway and it was still playing, so I crossed the street. Still playing. I moved behind a tree- still playing. I walked West, which is at a right angle to the original path and it kept playing, so I reversed my direction and walked East. I walked until my house was between me and the BT receiver which, unknown to me, had fallen off of the box it had been placed on. Still played, never cut out and never had a single hiccup so I walked to the point where I had a straight path to the receiver and went back, counting my steps- I was 60 yards from the BT receiver!
I listened to the sound quality and decided that it was better than I had expected- the bass and treble were there, which is more than I could say for the other BT devices I have used and after I installed it the next morning, I walked in a zig-zag path through the gym, which has a full-size basketball court with about 15' of space around the perimeter- never dropped out. I went through the doorways at the far end and it never dropped out, so I contacted the facility manager and showed him how to pair to it and how it held onto the signal. I have had zero trouble calls and these are people who wouldn't hesitate to let me know if something wasn't working.
I bought another BT receiver to test for another customer who wants to put his turntable in a room that can't easily be wired to the basement rack where the other equipment lives, including a Denon AVR with BT. I tested it by connecting the Rec Out from my Sony ES integrated amp which I use for its phono section since I no longer have an actual preamp in my system, only a Yamaha MusicCast WXC-50, my Parasound A23, speakers and a few sources. I paired the BT piece to the Yamaha since it can transmit OR receive and started playing an LP. Sounded good, no objectionable lack of highs and the bass is a bit accentuated. I don't know if this is intentional, but it didn't hurt anything. I haven't tried it with headphones but, since I don't listen with them unless I'm troubleshooting a noise/distortion problem, I don't know that I really need to. I did reconnect the integrated amp to the MusicCast Aux In and found that the bass IS accentuated and the highs are a bit softer, but it still sounded better than any other BT device I have used on my system. I plan to use pink noise so I can measure the response with/without BT.
The piece I used is from a company called Miccus, based in Detroit. I had found that the first one had an unacceptable announcement for 'Paired' and 'Un-paired', so I contacted the company and they surprised me by responding to my e-mail within a half hour with instructions for the new feature of turning off the announcement.
It has stereo 3.5mm input and output jacks, as well as optical input and output. It can pair to two devices at one time, transmits OR receives and comes with a short SMA cable so the antenna can be mounted outside of a cabinet. If a longer cable is used, it can be located closer to the transmitting/receiving device.
The one I received on Tuesday cost $49.99.
https://en.wikipedia.org/wiki/Bluetooth