Test: Comparing an AV DAC sound to a Pre-amp

I have a Proceed AVP (driven by a Theta Dreadnaught and Aerial 10T's) and a Meridian 508.20 DCP with the 24 bit upgrade. I'm wondering this: Would a preamp such as a Levinson or Rowland be a major improvement in sound warmth over the analog AVP connection I use now?

I'm looking not just for comparisons to those two pre amps, but any suitable preamp comparisons. I guess the question assumes that someone has at least heard the AVP long enough to know its sound. (If it matters, I use Audience and Cardas GR IC's and Audience speaker cables.)

I appreciate any experience you can provide. I like the Proceed sound on 2 chanel, even without a pass through. Yet I can't help but believe that a major improvement is in store just the same. Thanks, Joe

Get a 568 and eliminate the AVP and the 508.

Since the 508.24 and the 568 basically sound the same. Unit to Unit may vary a little bit.

Problems solved and cutting the treble with the 568's tone controls really helps the 10T's sound richer. They have a thin midrange.
The AVP-2 is said to be a big improvement over the AVP, and to use the same DACs as those used in the Levinson. The AVP-2 remains a bit pricey, though. A Krell 5.1 HTS might be a cost effective upgrade, especially if component video switching is a consideration. I have a Proceed PAV/PDSD combination and wonder if the DACs in an AVP-2 might be superior.

Thanks for your input. I appreciate it. What about this. What level of quality increase in the sound could I expect from adding a better controller vs a 2 channel pre-amp?