Audio Settings in Preferences--some questions

I'll try to answer in my non technical terms.  Using the higher rates allows you to mess with the files more and each time you do so, they will be rounded off to the nearest common denominator on your results.(remember digital is just "0" and "1")  Therefore, if you do A LOT of messing around, they will be rounded off several times...either to the "nearest 0 or 1...if that makes sense. After awhile, your file may "stray" from what it was originally, if it has been averaged or rounded off a couple times....i.e...by processing your audio.  The more presice the recording method, the smaller degrees of what thing get "changed" when "rounding off".   Think of a square wave or stair steps...the smaller the "steps" , the lesser amount of change will take place of the overall picture, if a step was slightly alter, omitted or rounded off.
Most likely you will not hear the differences on immediate playback of something freshly recorded, but the idea of a cumulative effect can happen.  People with 'ears' claim in critical areas like reverb and cymbal tails, the idea of what I'm talking about becomes more audible.
 
Therefore, generally speaking as I understand, if you've got the computer horsepower, go for the highest it can comfortably handle.  Otherwise back it down (leave the 64bit engine off, etc), but I'd stay at least 24 bit as a min.
 
There...I "hacked" thru that explanation...   not necessarily technically accurate, but trying to give a picture.
 
btw...it's 44.1...not 41

Griz,
a lot of these topics have been covered in other posts, but here we go.
 
1.  24 bits is what your ADDA interface is set to, so SONAR takes its que from that.  You can change it w/ your interface software.  64 bit double precision engine is what SONAR processes the sound with - hence the "double" the usual 32 bits.  Basically it means less rounding errors when the math doesn't divide in wholes.  If you are looking for Pi, you can go much farther down into the numbers.  Theoretically, it should deliver a more faithful sound when you mix or apply effects.  My suggestion is to try it and if you hear a difference for the better, use it.  Note that there were some problems w/ it in X3, causing some people problems.  I don't know whether X3D (coming soon!) fixes that.  Again, try it.  Me, I use it.  It puts no real strain on my computer, so, why not?
 
2.  Sample rate.  Lots of opinions on this.  Again, if you hear a difference, use what sounds better.  Lavry, maker of boutique ADDAs, has an old white paper saying the best sampling rate is in the 60s.  Higher and there are problems, and lower rates cause problems w/ the filters.  However, today, most of the early filter problems are solved, even for low budget stuff.  People used to claim they could hear a difference in some makes between 40s and higher rates, esp. lower budget gear.  On the other side I interviewed Rupert Neve and he declared low sampling rates were the problem.  Of course, he also said the only digital, on/off application he was familiar w/ was morse code he learned in WWII (royal signal corp).  I do trust his ears, tho, even tho he is in his 80s.  At first glance, using higher rates seems obvious, but I'm not sold.  I record at 44.1.
 
3. Render.  Again, this has to do w/ upsampling for anything other than mere playback - how much math is used to combine all the various things during mixing.  32 bit is pretty standard these days, which is what I use.  I suppose I should use 64 bit, but I edit in an old Sound Forge which defaults to 32 bit.  Never had a problem and I can pull in files from SONAR directly.  It just makes my life easier.  As far as importing - I use original file depth.  Makes no sense to re-render the file since you are just using it to playback.  It will get rendered at high rate/depth like all your 32 bit files.  Makes no nevermind as it sits on the timeline.
 
Lots of fun stuff here and opinions and even some facts (I may have gotten some wrong in the above and I'm sure I'll be told about it).  Read, ingest and then figure out what system is most comfortable to you.  Higher file quality is good in theory, but sometimes it is easier to use lower settings.  For the most part, if you did blind tests, most people couldn't tell the difference, I would bet.
 
have fun
 
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