No, I don't normally run that low - usually 32 or 64. But a lot of my projects will actually play smoothly at 16 with half a dozen synths and mostly just Prochannel FX and a lightweight reverb.
 
SONAR reports just 2 samples higher RTL than CEntrance, but there's a catch... that's a digital loopback with no D/A/D conversion. Comparing apples to apples with your 64-sample buffer and the converter latency included, the measured RTL is 213 samples = 4.4ms at 48kHz. Still smokin' thanks to the PCIe bus interface.
 
I just couldn't resist pulling your chain with that digital loopback and 16-sample buffer. 

DeeringAmps
ASIO; RME are the drivers by which all others are judged.
You can do the "loop back" test, it will be spot on; sample perfect.
Literally I never have a "sync" issue with either the UFX or the Babyface.
Oh, and did I mention; RME, ASIO, the BEST!
Make sure "Use reported Latency" is checked.
If you're using WDM, that's you issue right there.
T

I switched to ASIO and the problem went away, but now it's dropout city. Even after raising the buffer size and all that. Keeps dropping out.

Have you run Latency Monitor to make sure there's no background interference from other apps.. I guess I don't need to mention shutting off wireless and internet as well. Another bug a boo with some machines is HDMI audio driver.

delete your aud.ini file and let SONAR rebuild it.
I've outlined how do it here http://forum.cakewalk.com/FindPost/3533449
You running the latest drivers?
 
T

Dropouts can also be occur when Playback I/O Buffer and/or Record I/O Buffer are too small for the given project load, e.g. the project runs a high number of audio tracks, Take Lanes.
 
Try raising the buffer size in Preferences>Sync and Caching>File System>Playback I/O Buffer Size (kb).