I use a Lynx L22 and Aurora 8 in a multicore 64-bit PC. The Lynx mixer application has counters for audio dropouts of each of its channels. When using Cakewalk SW synthesizers Rapture and Z3TA+2, these counters indicate the occasional occurrence of audio dropouts, some of which are audible. In contrast dropouts do not occur when using my other SW synthesizers (the host of which is Sonar X1 64-bit):

Alchemy (64-bit)
Korg legacy analog and digital synthesizers (32-bit, used with Jbridge in Sonar)
LinnPlug RMV
Iris (64-bit)
and a few others

Any insights?

I'm having a lot of dropouts using X1 in ASIO mode. But in MME mode it works flawlessly.

Sonar overall is very sensitive to dropouts. Audio engine is not the best. They are doing something wrong with how softsynths are handled.

When I was testing firewire interfaces they were the first that had reported different latencies for in and out.

I could run one of the tutorial projects that come with Sonar, some 10+ audio tracks ot so with 128 samples latency setting without a crackle.

When I had an empty project with one simple softsynth that came with Sonar I could not run that with 128 samples, I had to increase to 192 samples.

Doing same with Reaper there were no problems with 128 samples.

They are calculating something wrong as I see it. I think they are inserting samples from the softsynth like it was coming from inputs and are dependent on roundtrip latency.

One of the reasons I ditched Sonar for Reaper.

Try increase latency for output to the same as where audio normally works and take that roundtrip and set to output latency. Then roundtrip will increase - but I find that necessary with Sonar.

I wonder if the vst handling is still done by some variant of the old fxpansion wrapper they 'integrated' back in the day? Is everything still wrapped into directshow?

Just for the record, I don't experience any dropouts with X1. I'm running a MOTU 828mkII on an older Core2Duo system under Windows XP. If I push the system as hard as it will go in terms of CPU usage and disk streaming a whole bunch of tracks, it might start to choke, but under normal operation it works great. Just my two cents...

Well I don't know my experience with Sonar is... weird. Sometimes everything works flawlessly sometimes I have to switch the audio driver from ASIO to MME. My last problem occurred a couple of days ago: while trying to reload some old projects after a loud sound the computer freezed. I've switched to MME and it works without problems.

Let me clarify a bit - having to increase latency to 192 was only with firewire interfaces I tested.

With RME internal cards 128 samples have always worked fine in Sonar for me. It report 128 samples for input and 128 for output.

Looking at what differentiated firewire from RME, it was the reported latency which was very different for in and out for the firewire interface. I think that has something to do with it.

If it was 112 samples out and 147 in or something like that.

So it seems that Sonar is inserting samples from synth into stream in a way that it needs the highest of the two. The synth becomes another input kind of and need latency setting that covers that.

That's my view anyway and one thing to consider if having problems.

So it might be depended on interface you've got.