I was using it with windows 7 and Sonar 8 with no issues but I've just upgraded to windows 10 and Platinum and though it plays back fine I cant record vocals. I think its the drivers ( they don't support windows 10) - but I just wondered if anyone is successfully using it? 
 
I have tried running in windows 7 compatible mode but with no luck

Just curious if these units used Avid drivers.  Windows 7 drivers should work.

Considering the following from the Avid d/l page, it seems clear that: a) the Win7 driver will NOT work under Win10, and b) they're not going to do anything about it, presumably due to the legacy nature of the hardware.
 
Same thing happened to me with the PreSonus AudioBox 44VSL, with the only difference being that Avid get points for clearly stating their position, while PreSonus stopped updated the "software/driver" over two years ago, but kept updating the download descriptor (claiming Win10 compatibility, when, in fact, it works for almost no one). Avid is sunsetting a legacy device and being straightforward about it. PreSonsus abandoned a relatively new platform and all of its users.
 
Count yourself fortunate in that regard. At least you know. I switched to a Tascam US-NxN interface and couldn't be happier. I was waiting on a sale price for the US-4x4, when I managed to snag a US-16x08 on an MF Stupid Deal of the Day for $200. Just about the best bargain I've ever gotten on anything associated with my ongoing all-things-audio GAS attack.
 
Windows Releases (click on a version # to download that installer)

• 6.1.11
  • Jan 19. 2016
  • This is the final driver release for the Fast Track Pro
  • Qualified with Windows 7, 8, 8.1
  • Note that Windows 10 (or later) is not compatible and will not be qualified
  • Fixed noise or pops/clicks when streaming with Fast Track Pro's S/PDIF output enabled

Odd that something will work in W8.1 but not 10.
Not  fan of Presonus hardware. I have a 1394 box they stopped supporting.
It seems RME is pretty much future proof.
 
 
 
 

Yeah, I've got one and I'm currently in the process of wondering if I need to toss it and buy something else.  I've got the latest driver installed and it works, but then for no reason will cut out and occasionally even crash the computer.  When downloading the driver the page actually stated that no further driver updates were going to be done.  So basically they've decided it's old and aren't going to support it anymore

My first interface was a Fast Track pro, so that's got to be a long time ago! I tossed it because it always would just stop working in the middle of things. It was embarrassing. It cut out once when I was using it for playback of dance music at a community event. I went home  and bought my Tascam us 1641 for $200 ,(same story as above!) It has never cut out, either has my Scarlett or even my pathetic Behringer uca201. M audio was struck from my list of products I will buy or recommend.  

You can save it and maybe use it for the pres. Don't chuck it right away.

I use a Fast Track Pro under Windows 10 64-bit as the sound-card for my back-up DAW/work computer and it works fine for listening to music and watching videos, etc.  I haven't had any issues at all, but I don't record with it.  One thing I found, though, is it does not like USB3 ports. 

I'm using a Fast Track Pro plugged into a Windows 10 64-bit PC for two years.  The hardware crashes every once in a while causing static or random pop noises, but I can unplug it and plug it back in and then it's fine.  It's been like that since I bought it when I had a Windows 7 PC, and when it works, it works pretty well.  To be honest, I use ASIO 4 ALL with it and not whatever ASIO drivers it came with ASIO Link Driver to bridge the gap between Windows Audio and ASIO.  My frmware is 1.0.2 and the driver package installed is 6.1.11.  Just for the record, AVID blows for not supporting what is claimed to be the "Final" version of windows, and what might be the last windows driver model necessary for many years, but even more so because they bother to tell you not to even try it.

It's usable under Win10, but not particularly pleasant. It has a bad habit of random crashes, and in Sonar Artist, I can only use it at 24/44.1, because the drivers seemed to be locked down to that.

Sadly this thing has reached the end of its useful life now that AVID's abandoned it because somehow I doubt that even if they abandoned it, they still wouldn't let anyone else support it with new drivers.