Looking to get the best out of Redbook Cd listening with Dac a d Transport under 5K?

Another option, if you're game, is to purchase an older multibit CD player and get someone to mod it.  I just had my Braun CD4/2 modded which now sounds completely different with open soundstage, far greater dynamic range and sweet sound signature.

Get a R2R Ladder Dac like Mojo Mystique 
V2Plus,
Jays Transport 
Black Cat Digital Cable 
Analog sounds with dynamics of cds

I didn't read every word, but if you have a full-blown Modwright Oppo 105, that's going to be pretty expensive to beat, IMO.  A friend of mine dumped his Linn Klimax for the MW 105.  The older ones, I can't say.  

OP - did you say you are using an Oppo now? And a modded one at that? If I read right - I'd say you already have your transport (assuming the mod didn't kill the digital outputs). Just get a DAC...

I recommend the Cambridge Audio CXC cd transport.  This transport does one thing only.  It reads CDs, nothing else and it does a fantastic job.  I think you can still find version 1 on Amazon. for $399.  The new version is little bit more expensive.  I tried this unit with a Rega Dac, a Micromega MyDac, an old Cambridge Audio Dac and a Musical Fidelity V90 Dac,  I was never disappointed on how well this unit read all my CD's

Best of luck.