2.7ms, 8.6ms Total Roundtrip.

Cakewalk Support, try this:
 
1. Open a new empty project
2. Insert an audio track
3. Drop an AVOX Sybil VST3 into the effects bin on that channel.
4. Switch AVOX Sybil off using it's "power" button
5. See the "Audio Dropout" error message appear.
This simple series of steps is causing the audio engine to stop unexpectedly every time I do it.   Whatever is causing this must have something to do with my other problem. 

Thanks for the speedy response.
 
Those values should be GREAT for latency, so something else would seem to be at work here.
 
What does LatencyMon or DPC Checker think of your base ability for your system to handle audio streaming?  (this is a reach, because you are as I understand it fine with the 32-bit version, as I understand it, but it might be nice to find out anyway).
 
LatencyMon and DPC Checker are freeware programs that measure aspects of your system's audio performance handling capability.
 
DPC Checker did not, last I checked, work properly in Windows 8.1, but does work fine in Win 7.  LatencyMon works in either and give you more info, as well.
 
I don't really think there would be any reported issues by either of them, if my understanding of things working OK with the 32-bit version of the plugins is correct.
 
If you DO decide to download and run either or both of those programs, you would just download and run them for 2-3 minutes, and you would be able to see if they thought there were any problems.
 
The link for LatencyMon is: http://www.resplendence.com/latencymon
 
DPC Latency Checker is: http://www.thesycon.de/deu/latency_check.shtml
 
Bob Bone
 

_________________________________________________________________________________________________________
CONCLUSION
_________________________________________________________________________________________________________
Your system appears to be suitable for handling real-time audio and other tasks without dropouts.
LatencyMon has been analyzing your system for  0:04:00  (h:mm:ss) on all processors.

_________________________________________________________________________________________________________
SYSTEM INFORMATION
_________________________________________________________________________________________________________
Computer name:                                        BYRDSTUDIOS
OS version:                                           Windows 8 , 6.2, build: 9200 (x64)
Hardware:                                             ASUSTeK Computer INC., M4A89GTD-PRO/USB3
CPU:                                                  AuthenticAMD AMD Phenom(tm) II X6 1090T Processor
Logical processors:                                   6
Processor groups:                                     1
RAM:                                                  16126 MB total

_________________________________________________________________________________________________________
CPU SPEED
_________________________________________________________________________________________________________
Reported CPU speed:                                   3211.0 MHz
Measured CPU speed:                                   4272.0 MHz (approx.)
Note: reported execution times may be calculated based on a fixed reported CPU speed. Disable variable speed settings like Intel Speed Step and AMD Cool N Quiet in the BIOS setup for more accurate results.

_________________________________________________________________________________________________________
MEASURED INTERRUPT TO USER PROCESS LATENCIES
_________________________________________________________________________________________________________
The interrupt to process latency reflects the measured interval that a usermode process needed to respond to a hardware request from the moment the interrupt service routine started execution. This includes the scheduling and execution of a DPC routine, the signaling of an event and the waking up of a usermode thread from an idle wait state in response to that event.
Highest measured interrupt to process latency (µs):   296.922909
Average measured interrupt to process latency (µs):   7.233788
Highest measured interrupt to DPC latency (µs):       293.414690
Average measured interrupt to DPC latency (µs):       1.893250

_________________________________________________________________________________________________________
 REPORTED ISRs
_________________________________________________________________________________________________________
Interrupt service routines are routines installed by the OS and device drivers that execute in response to a hardware interrupt signal.
Highest ISR routine execution time (µs):              55.742136
Driver with highest ISR routine execution time:       Wdf01000.sys - Kernel Mode Driver Framework Runtime, Microsoft Corporation
Highest reported total ISR routine time (%):          0.005129
Driver with highest ISR total time:                   ataport.SYS - ATAPI Driver Extension, Microsoft Corporation
Total time spent in ISRs (%)                          0.008136
ISR count (execution time <250 µs):                   19890
ISR count (execution time 250-500 µs):                0
ISR count (execution time 500-999 µs):                0
ISR count (execution time 1000-1999 µs):              0
ISR count (execution time 2000-3999 µs):              0
ISR count (execution time >=4000 µs):                 0

_________________________________________________________________________________________________________
REPORTED DPCs
_________________________________________________________________________________________________________
DPC routines are part of the interrupt servicing dispatch mechanism and disable the possibility for a process to utilize the CPU while it is interrupted until the DPC has finished execution.
Highest DPC routine execution time (µs):              387.326690
Driver with highest DPC routine execution time:       tcpip.sys - TCP/IP Driver, Microsoft Corporation
Highest reported total DPC routine time (%):          0.045746
Driver with highest DPC total execution time:         dxgkrnl.sys - DirectX Graphics Kernel, Microsoft Corporation
Total time spent in DPCs (%)                          0.094109
DPC count (execution time <250 µs):                   187452
DPC count (execution time 250-500 µs):                0
DPC count (execution time 500-999 µs):                43
DPC count (execution time 1000-1999 µs):              0
DPC count (execution time 2000-3999 µs):              0
DPC count (execution time >=4000 µs):                 0

_________________________________________________________________________________________________________
 REPORTED HARD PAGEFAULTS
_________________________________________________________________________________________________________
Hard pagefaults are events that get triggered by making use of virtual memory that is not resident in RAM but backed by a memory mapped file on disk. The process of resolving the hard pagefault requires reading in the memory from disk while the process is interrupted and blocked from execution.

Process with highest pagefault count:                 taskhostex.exe
Total number of hard pagefaults                       2
Hard pagefault count of hardest hit process:          1
Highest hard pagefault resolution time (µs):          703.663968
Total time spent in hard pagefaults (%):              0.000051
Number of processes hit:                              1

_________________________________________________________________________________________________________
 PER CPU DATA
_________________________________________________________________________________________________________
CPU 0 Interrupt cycle time (s):                       1.555786
CPU 0 ISR highest execution time (µs):                6.152912
CPU 0 ISR total execution time (s):                   0.000052
CPU 0 ISR count:                                      12
CPU 0 DPC highest execution time (µs):                387.326690
CPU 0 DPC total execution time (s):                   0.308322
CPU 0 DPC count:                                      92373
_________________________________________________________________________________________________________
CPU 1 Interrupt cycle time (s):                       0.427797
CPU 1 ISR highest execution time (µs):                31.000623
CPU 1 ISR total execution time (s):                   0.000152
CPU 1 ISR count:                                      27
CPU 1 DPC highest execution time (µs):                88.975086
CPU 1 DPC total execution time (s):                   0.004195
CPU 1 DPC count:                                      659
_________________________________________________________________________________________________________
CPU 2 Interrupt cycle time (s):                       0.318266
CPU 2 ISR highest execution time (µs):                33.170975
CPU 2 ISR total execution time (s):                   0.000370
CPU 2 ISR count:                                      71
CPU 2 DPC highest execution time (µs):                90.826534
CPU 2 DPC total execution time (s):                   0.004006
CPU 2 DPC count:                                      702
_________________________________________________________________________________________________________
CPU 3 Interrupt cycle time (s):                       0.355116
CPU 3 ISR highest execution time (µs):                31.132358
CPU 3 ISR total execution time (s):                   0.000432
CPU 3 ISR count:                                      84
CPU 3 DPC highest execution time (µs):                105.493616
CPU 3 DPC total execution time (s):                   0.005209
CPU 3 DPC count:                                      812
_________________________________________________________________________________________________________
CPU 4 Interrupt cycle time (s):                       0.545667
CPU 4 ISR highest execution time (µs):                31.507630
CPU 4 ISR total execution time (s):                   0.003436
CPU 4 ISR count:                                      580
CPU 4 DPC highest execution time (µs):                106.895048
CPU 4 DPC total execution time (s):                   0.021671
CPU 4 DPC count:                                      2349
_________________________________________________________________________________________________________
CPU 5 Interrupt cycle time (s):                       2.421488
CPU 5 ISR highest execution time (µs):                55.742136
CPU 5 ISR total execution time (s):                   0.112731
CPU 5 ISR count:                                      19116
CPU 5 DPC highest execution time (µs):                167.615073
CPU 5 DPC total execution time (s):                   1.011846
CPU 5 DPC count:                                      90600
_________________________________________________________________________________________________________

Thanks, Bob.  All of this will be helpful to Cakewalk and hopefully will get them to take another look at the interface between Sonar and the Antares VST3s.  All other plugins seem to be working fine.
 
Thanks again.