Here is an interessting experiment we made.
We have a PC running Nuendo 3.0.2 AND PT LE 7.1 with the Music Production Toolkit at the same time.
Nuendo was using an RME HDSP 9632 and LE a DIGI002 as audio hardware.
We took the same file (a stereo mix we did) and played it from the TOSLINK of the 002 and the coaxial S/PDIF of the 9632 into the same converter, a RME ADI-2 at 44.1k.
The ADI-2 has a switch at the front so you can change between optical and coaxial S/PDIF input, enabling us to rapidly switch between Nuendo and PTLE.

Now, both faders in the respective programs were at 0, the file was the same, with the difference being PTLE cannot play stereo interleaved files and Nuendo can.

The observation we made was that you can tell blindly, which program you are using as your playback engine, we had someone toggle the switch on the ADI-2 a lot, so we didn't know what was playing any more, and then listened to the playback and could very soon tell with 100% accuracy if PTLE or Nuendo were playing.

To me Nuendo had fuller, tighter bass and PTLE slightly more aggressive upper midrange, sounding more like your average radio-pop/rock record.

Anyone made similar observations?

Cheers,
raphbaph