Not sure. Audio in general is pretty subjective. I can hear it, but... I couldn't decribe exactly what's going on in concrete terms.
Here are my experience's, though.
1) Macke VLZ's into Digidesign 888/24's vs. Art Tube MP's into Apogee AD.
OK, the VLZ's and MP's are horrid pres, BUT the Apogee tracks are very noticeably more detailed. Like a layer of dust was wiped off a window. The Apogee is also the sytem clock- and the whole rig sounds like poo poo when it gets switched off and the system (Pro Tools Mix:24 Plus) reverts to its internal clock.
2) Digi 002 onboard convertors vs. ADAT LX-20 convertors. Both fed by preamps from a Soundtracs SOLO MIDI or
a Tascam M520.
Less obvious difference, but what is an obvious difference is when I slave the Digi 002 clock to the ADAT! Again, a layer of dust comes off what I thought was a clear window of sound. I couldn't believe it and wasn't expecting it, but its true.
3) RNP into Digi 002 line inputs and convertors vs. into a TC finalizer.
Wow. The RNP is a pretty glossy preamp and sounds good through anything, but through the Finalizer it takes on an even larger, clearer sound.
Enough for your mom to hear? Probably not. Enough to make a noticealbe difference when magnified by all the tracks in your session? Definately.
What seems to be the biggest difference for me is when I clock may system to a good clock. The Finalizer was my clock before it broke and even improved the playback of sessions recorded to the Digi 002's internal clock. When it broke I was surprised to find the ADAY clock had a similar effect. Not night and day differences, but I like using my gear to its greatest potential and I was amazed at the easily noticeable clarity of stereo field and... realness... that was offered by useing the external clocks.
Every little bit helps.
Take care,
Chris