I was playing the CD version of an album we recorded in 2010 
https://soundcloud.com/john-vere/sets/the-uncle-ruckel-album-2010
 
Of course one is never completely happy with what we have created. The temptation to re mix was strong!!  So I loaded the original CWP files into Sonar Professional and wow! There was this huge improvement compared to the CD. Everything was clear and punchy. Why? I started comparing things. 
 
This album was recorded using Sonar 8.5 Pro 32 bit using a Tascam us1641. @ 44.1.  My playback system in my studio remains unchanged other than my Scarlett interface replaced the Tascam. I don't think that would make a difference to playback quality so I ruled it out.  The songs are under 12 tracks and mostly audio. The only  midi is the Keyboard part and I replaced the Kick. So these are basic live band recordings with only a Lexicon reverb and Sonitus Delay for effects. There is also a Sonitus compressor in a few track bins. Master bus has LP64 multiband. I guess they where all 32 bit so that could be a factor? 
 
I so I dropped a WAVE master into the same song and soloed etc. There is a noticeable difference. 
So is this difference the new audio engine? Or is there that much difference between 32 and 64 bit??
I'm not using the 64 bit rendering option.
Anyhow what I'm going to do is re export the songs and burn a new CD tonight and see if this is true.  
 
PS- the original CWP files loaded into Sonar Professional without any fuss. No warnings or difference other than the screen size was smaller. That's a big jump in Sonar versions without a hitch.  
 
 

20 - 40% better? Sorry, couldn't resist...
 
Honestly, I don't think you can rule out the interface change. Even though you aren't using the preamps, the converters are still in use on playback.
 
It's also possible that the engine has been improved over time due to bug fixes and enhancements.
 
One last thing: is there any possibility that the audio was modified prior to getting put on CD? A limiter or additional compressor?
 
Regards,
Dan
 

One last thing: is there any possibility that the audio was modified prior to getting put on CD? A limiter or additional compressor?
 
Yes all songs are opened in Wave Lab to check the RMS level and top and tail. If the RMS level is low  then songs are run through the Steinberg Loudness Maximizer. 
So this is possible and I'll have to make some checks on this. 
 
As I compared the original master wave files AND the CWP project using only the Scarlett that rules out the interface for sure. 
It's a noticeable difference. Almost like the difference between a wave and MP3. 
 
I was just wondering if anyone feels there could be an improvement in sonic quality with what I understand is a new Audio Engine since 8.5. But I will run some tests and see if this is a mastering issue first. 
I still have 8.5 installed as I do this to get True Piano's and a few other missing items I don't get with my currant version. A simple test would be to export the same project from both 8.5 and Professional. 

dcumpian
Honestly, I don't think you can rule out the interface change. Even though you aren't using the preamps, the converters are still in use on playback.

Converters and clock could make a significant difference.

You did use the Tascam to record rather than the Scarlett.  I noticed that songs I recorded using an Aardvark Q10 sound better playing them back through my Fireface 400.  Plus, if you're playing your tracks using the ProChannel, that could make a difference.

I see the point. I still have my Tascam so another test would be to export the same song and switch out interfaces. 
Thanks all for the input. 

Of course the songs were recorded with the Tascam. And the projects won't have anything different as I am opening the absolute final versions so they open "as is" therefore should be what was exported. And I now remember that by the time I finished the album I was working with W7 64 bit and the 64 bit version of 8.5. so that's not a factor either. 
 

It's the 64 bit precision cowbell.. 

Doktor Avalanche
It's the 64 bit precision cowbell.. 

For me it was my personalized hover car.
 
Y'all got one too?

Doktor Avalanche
It's the 64 bit precision cowbell.. 

Of which you can never have too much.