When I get time on my days off I will give this a whirl with my VS-100.

I revisited this based on this post by Brundlefly and downloaded the "CEntrance ASIO latency tester" It gives identical results and is quicker to check/modify routing and buffer settings on the interface.
 
One thing that did occur to me with mine is the internal DSP. When internally looped back, it seems the DSP routing is bypassed completely (simple in->out engagement), but the extra buffer is used to accommodate the internal DSP processing (and apparently not reported to SONAR). I tested several buffer sizes at all rates and the offset was identical for each. Internal loopback is off by 6 samples, external 76.
 
I did not check the internal VRM feature because I was too lazy to find my splitter to get the headphone out routed back in, and that is a "mixing only" feature anyway.

I had forgot about the CE tester. Ran it on my Babyface and it picked up the 1 sample difference that Sonar was missing.
T

Yes you can use the Centrance or the Oblique testers they both do the same it seems. 
The visual loop back test is more involved but the advantage is it shows you fairly quickly that something is off. 
 
Out of researching for this thread I've certainly found that my Tascam us1641 is now at least not the door stop I thought it was. I recorded and mixed a 10 song Jazz 5 piece band on Monday and Tuesday without a hitch. So I'm still getting my $200 back from it ten fold. To bad it caused so much grief with the old drivers. Thank you Tascam for taking the time to update drivers for your old stuff. 
 

I was thinking my us1641 was headed out the window, too, until I saw that Tascam released new drivers for it! What a shock! I am really pleased with them, again, after a long slump. I am hopeful that their involvement with Cakewalk will be really good for us.
 
I can't change from 44.1 to 48kHz, however and wonder what rate you're using John? I do seem to recall that Sonar could change the rate but the us1641 might show that it was changed, back when I first got it in 2008.
Michael
 
Thanks for the Centrance utility, Mike! I'll check it out on my laptop today and hopefully the new i7, after I swap things around in my studio.
 

Michael, I will see if I can switch to 48 with the Tascam. I seem to remember that this was an issue for me too. My old Sound Blaster projects where all 48 and I think they barfed with the Tascam.  Because my Yamaha 01V digital mixer only works in 44.1 I'm sort of stuck at that clock rate  so  have not used 48 for a long time now. I'm moving towards changing this as I kinda like 48. Having the extra inputs of the Tascam and it now working nicely changes my game plan so I might not need the 01v anymore. But if the Tascam is also stuck at 44.1 that's a bit of a bummer.   
 

Supposedly (in the original manual), the us1641 detects and selects whether you're inputing 44.1 or 48kHz from the DAW. What I wonder is how to have it convert audio to 48kHz!
I am still hopeful that this latest driver will allow me to use it for a while longer......I like it's features, too! and not needing to replace it, allows me to expand in other studio areas, which would be great.
 
Michael

+1, if SONAR has no project with existing audio loaded, it will allow you to shift sampling rates inside SONAR. Once audio data is present, SONAR locks itself to match (and will also lock the interface if they talk correctly).
 
There are a few third party tools which will batch convert more quickly; but within SONAR itself, it requires exporting the audio and doing a SRC on export to shift rates. I have never actually done this, so not sure if this also requires a new project to be created and have the audio imported. In such a situation, I will work the project through and then SRC the final product (audio for video use in another program).

Thanks mettelus! I will try that out this afternoon and see how that goes.
Michael