Thanks for the suggestions, Sheanes.  When I edited my cache settings I made sure these were unchecked so that wasn't the issue, sadly.  By the way, what do you have the caching set to?  Mine was 512 when I used the Focurite Liquid Saffire 56 (my former unit).  I have since changed it to 1024 as part of my experimentation but that hasn't helped.
 
I took your suggestion and changed everything to my desktop.  Same thing.  Tried a new song, moved it to desktop...same thing.
 
Not even close to giving up, though!  lol
 
I will say the Apollo does make the song sound amazing.  I liked it before...it's even punchier and cleaner with the Apollo.
 
 

I noticed that if I play the songs with no plug ins the drops stop.  To me that sounds like I am running out of DSP to run the plug ins.
 
I have a Quad pcie card and I have played this song hundreds of times.  The Apollo 8 is a DUO.  I am wondering if the Apollo is trying to run all the plugins from 2 Cores rather than letting the QUAD card do its share of the work.  MY understanding is that with my set up I have effectively a 6 core system so I should be able to run a ton of plug ins. 
 
I am trying to check in with UAD support to see if there is a setting I may have missed.  Will let you know what I find out.

Friendly update.  Not sure what I did right but things seem to be working really well now.  I am sure a lot of it was a steep learning curve.  The only thing happening now is that the song stops when I add a new plug in while in play, never used to happen, and my icons are not present when I save a song (project or bundle).  The second thing is odd, not a problem per se.
 
 

Not sure if anyone is interested in my journey as I get my new gear set up but here is the latest:
 

• Built new computer (intel i7 6700K Skylake Quad Core, Gigabyte Z170X Gaming 7 MB, 32 Gb RAM)
• Upgraded to the latest version of Sonar (Sonar Platinum 22.10.0 [2016.10] 64 Bit)
• Fresh install of Windows 10 Home edition 64 Bit
• UAD APollo 8 Thunderbolt

• Worked through a lot of minor but annoying issues.  Forum members were incredibly kind sharing their settings and configs of their ASIO drivers which helped get me into what I would describe as a moderately stable place.

 
As of now I am able to get through a recording session and playback of any song I have done so far with no dropouts.  That being said, if I try to do any on the fly editing (adding plugins, editing plugins, etc) the song stops immediately.  It doesn't crash, though.  I just hit space bar and it picks up from where it left off.  As long as I don't do any real time/on the fly messing around I can get through what I am trying to do.  This is good, but not ideal.  
 
Still looking for any thoughts from anyone who has been there/done that.  Hoping this helps anyone else looking to build a similar set up!
 
One other thing...I was reading about ASIO4ALL drivers.  Any thoughts?  Good?  Bad?  Ho hum?
 
 
 
 

After some time getting to know my system I am learning that the more I can get off of Sonar the better off I am.  I am using Sonar almost totally as an audio recording delivery system and all the mixing and EQ work is being done via UAD/Apollo.  Admittedly, I am a UAD devotee but the fewer things I use Sonar for the fewer crashes I get.  
 
While it is possible I have something fubar going on with my system and I just have not figured out what... I am still getting multiple instances per session where Sonar will crash with no reason given.  I can't predict when this will happen, I have to save literally every time I do any edit for fear of losing it and having to start over.  The less I use Sonar to do any edits the few crashes occur.
 
This is a sad post, I get it, but this is my life with this product I love/despise.
 
:(
 
 

...so I went out and bought a new SSD hard drive, reinstalled everything...Windows 10, Sonar Platinum, UAD latest version, etc.  Still having incredibly frequent dropout.  I have noticed that the dropouts only seem to occur frequently when using the UAD plugins.  If I turn them all off and only use Cakewalk plugins or Waves or S-Gear or anything else things seem to be fine.  
 
I will be bringing that up to Cakewalk support and to UAD support.  In the meantime Win 10 has this annoying habit of showing a pop up box at the lower right each time a dropout occurs.  Anyone have any idea how to shut that down?

Man, I wish I could help. I have a "Studio B" that's based around an Apollo Twin USB and it runs smooth as silk. FWIW I don't use the plug-ins as VSTs, I do the Console thing and you probably do too...I assume your systems meets the Windows specs on the UA web site, including the Thunderbolt-to-Thunderbolt adapter:

• PC computer with built-in Thunderbolt 3 via USB-C port
• Windows 10 w/Anniversary Update (64-Bit Edition)
• Qualified Thunderbolt 3 to Thunderbolt adapter* (sold separately)

*See the Apollo Thunderbolt Windows Compatibility article for details
 
Because I haven't had problems I can't say "yeah, I had a problem but I fixed it by..."  However, I did notice you have a gaming card. I don't know if it installed "HD" drivers but I have found out the hard way that simpler cards are better, and lacking that, disabling any drivers added by the card as part of its software can be really problematic. The reason why is gaming cards prioritize frame rates over audio. There are even cards that basically just stop audio streaming when they feel like it, so the only solution is either a) really high latency settings or b) having dropouts at lower settings.
 
 

Bummer.  I got this MB because I thought it would be a kick butt board and would position me with a strong system for the next few years.  I did go and remove all the NVIDEA programs related to 3D or gaming and left just the graphics program functioning.  I also removed all the Audio programs that were loaded from the CD so the only audio option I have is UAD.

Holy Baloney!!!!
 
So I followed some advice gleaned from the ever knowledgeable Mr Anderton and removed any audio programs that looked to be gaming specific (any audio other than UAD and any graphics from NVIDEA that were not needed) and then set CPU parking to 0 (default from 64, or 100%) and then set some max power options from 5% to 100% as stated in another post....problem seems to have vanished!
 
While a song was playing I deleted each plug in (there were a lot) and no impact on performance.  No drop outs.
I added plugins while the song was playing...no drop outs.  I copied and pasted a simple UAD EQ plug in across 24 channels...no drop outs.  I edited plug ins while the song was playing...no drop outs.
 
This just happened so I am not sure if I will eventually hit a limit and see the issue again, but at least for today this is the best experience I have had in many many months!!
 
 
 

For the love of....
 
So my joy lasted exactly one reboot.  As soon as I rebooted my system the same old garbage started happening.  Back to being a sad pup.