Whether a considering a pre/pro, or nice player like the Oppo, the big audible gains are found elsewhere.
Addressing the room, and both it's decay characteristics in the LF, and (primarily) three treatment panels/absorption locations, would likely transform your system's attributes into the stratosphere. You've got all the LF capability in the world, yet I'd guess it's not fully realized due to a problematic lack of LF damping.
I've got an Oppo too, they're superb. High-end playback, made affordable. Plus, it'll do anything/play anything. The quality DAC, to analog XLR outs, is so sweet. Spend some time with the manual, the capabilities are just great.
Also, a properly optimized SEOS based approach would outperform your current set-up, IMO. But, I hesitate to recommend any hardware based purchases until the LF decay (bass trapping) is addressed. That's my take, fwiw. I've given much thought as to a ground up room build, and I think you missed a killer opportunity when building the walls to incorporate some simple damping techniques. But I realize you had other priorities, and that cool too. The room turned out nice, I just would've incorporated some other acoustic elements into the boundaries.
A SEOS approach would lower distortion for realistic or live type playback levels. The B&Ws are great, but a well executed compression HF approach can achieve wonderful things."honky/bright/distorted sounding"
Not at all. Plus the controlled directivity inherent to the SEOS design, helps minimize the room's negative influences and can likely increase IACC, and thus a higher level of resolution into the recorded event. Also, properly set up, and by utilizing time-intensity trading
, one can create a huge sweet spot, whereby the image is stable over a big listening area.
Bill Waslo describes it here
All said, if you really like the B&W mains, I'd not change.
Best of luck