To Hans Wetzel,
Great review of the Definitive Technology BP-8020ST SuperTower loudspeakers. I've been looking to upgrade from my PSB Image T5. I've looked at the Mirage OMD-15 and I wonder if these are speakers you would recommend since you have the larger OMD-28s. I am also considering GoldenEar Technology's Triton Two or DefTech's larger BP-8060ST or BP-8080ST. These will be connected to my PrimaLuna ProLogue Two with a Logitech Squeezebox.
While I haven't heard the PSB T5s that you own, I have heard several Paul Barton designs, as well as talked to the man on one or two occasions. I am confident in saying that you have a very good pair of speakers, and while you will probably hear some differences in the list of competing products that you mention, odds are that in some ways you'll be moving sideways, rather than upwards, in terms of sound quality. You've mentioned a number of loudspeakers here, and so I'll tackle them in order.
While I owned Mirage's final flagship loudspeaker, the OMD-28, I never had a chance to listen to the OMD-15 ($2500/pair when last available). They look to be a relatively easy load to drive, and by reputation I hear they have surprisingly deep bass. You would need to take some time and effort to set them up correctly to maximize their performance, as they'll definitely need breathing room due to their omnidirectional dispersion. Their imaging is . . . different. Different than just about anything. If they're like the OMD-28s I used to have, they probably sound enormous, but at the expense of image specificity.
Which leads me to the DefTechs that you mention. The Forward Focused Bipolar Arrays found in their SuperTower series, whereby the rear drivers are 6dB down from the front drivers, works very well. They create a soundstage which is almost as cavernous as the Mirage OMD-28s I used to own, but with terrific imaging to boot. It's worth noting that they do have a crisp, crystalline sound to them, perhaps sounding a little sharper and brighter than your PSBs. But this will be offset by the tubes in your PrimaLuna integrated amplifier. I think any of the SuperTower models that you mention would compliment your existing setup.
As for the GoldenEars, they have a different personality, which I found while reviewing their Triton Three loudspeaker. They have a more sophisticated disposition, as their High Velocity Folded Ribbon (HVFR) tweeter has a smoothness that the DefTechs do not. This quality is not necessarily better, just different. The slightly warm, smooth, laid-back character of the GoldenEars probably falls to the one side of your PSB T5s, while the more strident and surgical character of the DefTechs falls on the other. Having reviewed a speaker in each line, I can say with confidence that you cannot go wrong here. High efficiency, active bass sections, and deeply capable everywhere else. My preference would be for the BP-8060STs, as their $2000/pair price, the same as GoldenEar's Triton Three, gets you that enormous bipolar soundstage, and almost all the bass of the larger 8080 model. But definitely listen to both lines of speakers before making a decision. . . . Hans Wetzel