Never owned a set, so I can't really comment.
So.... I replaced the Sansui A40 with vastly more powerful Yamaha RX-V663 AV receiver. And the B&W DM302 sounded much better ever since! Thanks, gdjacobs! I think the 25 WPC Sansui just couldn't handle the 3 ohm impedance drop, while the 95 WPC Yamaha can.
Trumpet-heavy songs that were previously unbearable with the BM302 driven by Sansui, now becomes more tolerable, especially Herbie Hancock's Cantaloupe Island and Shirley Bassey's Goldfinger. However, I noticed significant soundstage depth reduction in The Coryells' Sentenza Del Core - Allegro, also in Princess Amidala's monitored heart beeps during childbirth in Star Wars: Return of The Sith. Fortunately, such thing doesn't happen in Infected Mushroom's Saeed.
Nonetheless, the overall sound becomes warm and pleasing with the more powerful Yamaha RX-V663. It should be noted that Yamaha RX-V663 has bright, sterile, and clinical sound, that makes JBL titanium dome tweeters --such as JBL 120Ti and JBL L20T-- fatiguing. With B&W DM302, it is a much different case: the entire sound becomes warm, airy, and pleasant to listen. In 2013 I auditioned a pair of midrange-heavy JBL 4315 driven by NAD C325BEE, and I was pleased by the resulting warm sound. Listening to DM302s driven by Yamaha RX-V663 reminds me much of that experience. I am mostly pleased by Miriam Makeba's Pata-Pata album. All songs in the album sound so natural, so warm, so smooth.
As for soundstage depth, all is not lost. Yes, I noted much soundstage reduction in The Coryells' Sentenza Del Core - Allegro and Star Wars: Return of the Sith. But I played Scorpio Girls by Supergroove. The song opens with the sound of running footsteps indoor, and much to my pleasant surprise, the sound really comes from behind the speakers! I never experienced this with JBL L20T driven by Sansui A-40, not even with JBL 120Ti driven by Sansui AU-7900. Also, in most songs, the 3-dimensional soundstage depth subtly appear. Not a "wow" moment, but subtle.
I mostly use Yamaha RX-V663 in pure direct stereo mode, but it also has Cinema DSP. And based on my short experiment with Supergroove's Scorpio Girls, Yamaha Cinema DSP actually deepens the sound stage. It's great, since I mostly play games with Cinema DSP activated anyway.
It's also interesting to note that clinically detailed speakers like JBL 120Ti and JBL L20T sound best when driven by the warm-sounding Sansui AU-7900 and Sansui A-40, while warm-sounding speakers like B&W DM302 sound best when driven by clinically detailed amplifier like Yamaha RX-V663. I have tried Yamaha RX-V663 driving JBL 120Ti, and the sound is fatiguing in the long run.
Anyway, should I be satisfied with Yamaha RX-V663? Or perhaps an external 5-channel amplifier would sound better? The RX-V663 has multichannel analog pre-outs, so I could use external power amp. Any suggestions?