As it's 2.4ghz it may also be partially spectrum pollution.

That said - that seems rather impressive for Bluetooth, I've had one reinforced concrete wall pretty consistently screw up most bluetooth signals in my experience, so I'd posit that you're getting unusually good reception there.

I wonder what strength the radios broadcast on. I do have a 2.4GHz wifi-router both downstairs and in the attic so you would expect no signal at all, given the situation. I'll admit that by this point it's extremely sensitive to spectrum pollution; a nearby laptop with wifi on will mess with it enough that it starts stuttering. My only issue with bluetooth is with Android; it semi-randomly likes to change pitch and speed by a little [1]. Very noticeable if you listen to electronic music. Had it with my previous phone (Android M, CM) and now with my current phone (also Android M, stock) and different devices (headphones, car).

[1]https://code.google.com/p/android/issues/detail?id=209473

Yeah, anecdotal but every friend of mine that complains about BT does it in relation to their Android devices.

I've heard a couple of complaints about Macs but they're rare.

Seems the Android BT stack is just more... flaky. I wonder why...

Android 1.0 to 4.3 (iirc) used Bluez, an open source implementation related to Linux.

Come 4.4 Google partnered up with qualcomm (again iirc) to write a new stack from scratch.

Iirc, there are multiple classes of bluetooth radio. And only one of them, that i have most often seen in the form of USB dongles, are wifi equivalent.