The last days I got my Sennheiser MB660 MS UC. At the first time I plugged it to my Surface PRO 4, running Windows 10 PRO Insider Preview Evaluation copy. Build 16281.rs3_release.170829-1438, who worked smooth on my Plantronics Voyager Focus UC. When running the dongle on the MB660 it works fine. The drivers got where they should, and the Sennheiser update installed the latest firmware for the dongle and headset.
But when I tried to use it with the dongle in the Surface, on bluetooth, and with my Microsoft mouse on bluetooth, well the sound in the MB660 was kind of crappy.
It looks to me kind of an IRQ conflict with the MS mouse on bluetooth. This worked just fine on the Plantronics, but it can be an driver issue maybe.
I have not digged into this to see what it can be, but I think it's strange. It can be the OS version that I'm running also. But as long I use the dongle it's just there.
The sound when watching NetFlix, HBO or listen to music on Spotify or do recording of soundfiles, this works just fine.
I do think that the sound when I use it on my cellphone to speak it gives me a feeling that I'm sitting in a room with no furnitures. But that migth be some settings that need to be adjustet. I'm useing Samsung S7 as my mobile, but there was no issue with my old headsets.
When I use it on Skype for Business, the one I speak to say the sound from me is not so good. It's clear but it kind sounds like I'm in a box speaking. I have also tried to use the cable but the same issue. The same thing there.
But all over the headset works just fine. If I shall roll the dice where 6 is top, I will give this 5.5. So why not 6? Well the price is one reason. I am sure you can get something better to the cost, but it's good.
Update 1. After working on my windows 10 build and got to reconfigure Windows 10, the driver works now just fine. The box speaking sound is gone. The people I speak to by Skype for Business say now that sound has been better. So there might have been a driver issue. There fore I have changed the score from 4.5 to 5.5.