According to an item on Yahoo, Homeland Security is advising to "immediately" uninstall Quicktime from Windows PC's due to security risk.  Also it was noted Apple is discontinuing support (new versions) of Quicktime for Windows PC's.
 
Here is the article:
https://www.yahoo.com/tech/us-advises-deleting-quicktime-windows-computers-201217977.html
 
 

To my knowledge, no. Sonar uses Windows' Media Foundation or DirectShow engines. You should not need Quicktime.
 
I have removed it with no ill effects.

I think sonar only ever needed quicktime if you were planning on doing video's with your projects.
I always skipped that part of the installation.
 
Steve

The subject is a loaded question. SONAR never required Quicktime. By default Quicktime is not installed.

I remember older versions (maybe 6 or 7) noting about QT.??  I've kept it installed since then.

It used to offer to install it for 32-bit only, as Quicktime was not ported to 64-bit until long after I worried about it - I never installed it and never had any issues, plus I run 64-bit anyways.
 
I USED to tell the installer for Sonar to go ahead and install it when I was running on XP with a 32-bit Windows, but that was MANY long recording/editing/mixing years ago. 
 
Bob Bone
 

Get some decent codecs, uninstall QT... although the vulnerability and risk to your computer wont really be to much of a concern for a while (I work in IT security).

markyzno
Get some decent codecs, uninstall QT... although the vulnerability and risk to your computer wont really be to much of a concern for a while (I work in IT security).

especially compared to flash and javascript ;-)

pwalpwal

markyzno
Get some decent codecs, uninstall QT... although the vulnerability and risk to your computer wont really be to much of a concern for a while (I work in IT security).

especially compared to flash and javascript ;-)

Dont get me started on un-patched versions of those!

As it turns out another program, "Discus" (CD Label and Jewel Case insert program) requires QT.  I'm going to uninstall that from my operational system (Win 10) and keep it on my Win 7 installation that I no longer go on line with (NIC is disabled).  I keep Win 7 as I need that for an RS232C application (the USB/RS232C adapter will not work on Win8/10) for my wife's Singer Embroidery machine to transfer patterns.  If Discus is ever rebuilt to not rely on QT then I'll consider reinstalling it.  Sadly, Discus is the best label program I've found. 
 
I have iTunes as I have an iPhone and I from what I remember the Apple updater has not been offering QT updates for quite a while (since I upgraded to Win 10 last July).  Possibly it is true they are going to discontinue Windows support for QT.