Spirit,
If your location did not change since you've introduced system alterations circa 2007 and continuing, then I would have expected you to have distinctly different preferences as your combination of gear progressed.
A key point here is that you started with a preference for analog with a Michell Orbe in place and the change introduced being ProAc to Zu Definition 2 speakers. With the Michell being a suspended sub-chassis turntable and belt drive and the Definitions capable of putting more deep bass energy into the room compared to the ProAcs, it's possible (even likely) that the colorations introduced by the turntable were exacerbated by switching to Def2s. Meanwhile, moving from the unsettled tweeter in the ProAc to Zu, going crossoverless and upgrading your optical disc player allowed your ranking of relative objectivity to change.
Now, once again you've introduced a large change in sources and the design differences alone will alter perceptions. You've moved from a very fine suspended subchassis turntable with "relaxed" drive characteristics to a slate-plinthed suspensionless turtable with the urgent pacing of direct-rim-drive. That's a pretty radical change and once again, it's possible that in your installation not only does the TransFi prove less pervious to structurally-transmitted bass energy, I would expect its timing to sound more correct, and that it will deliver more of the dynamic burstiness that is also natural for Zu. In other words, the Salvation will be more like digital in its good aspects, while being solidly analog in tone, finesse and musicality.
Now, if your question is, "Are the Def2s obscuring some of the information the Salvation sends down the pipe?" Sure. But so does any speaker. After all, the loudspeaker -- even a good one -- is the most egregious contributor of distortion of all the gear in the chain, and it functions into an acoustic space interface that further influences it. Will Def4 resolve more of what your TT is feeding it? Yes, and I have no doubt you will recognize this within 13 seconds of dropping the stylus on wax through your new speakers. As I've written before: I can't think of a single way in which Definition 2 is equal to or better than Definition 4, other than used 2s being cheaper!
But it's not going to be just what else Def4 resolves that Def2 doesn't. That's appreciated and valuable. But for me the two most beneficial improvements are in the audibly tighter unity behaviors of the drivers working together, and that very much applies to the 12" downfiring sub compared to the 4x10" rear-firing line array in Def2. The second thing is that while Def4 doesn't extend any higher than Def2, it sounds like it does because the nano FRDs are so much more agile up to 13kHz and the Radian 850 compression tweeter is as beautiful as it gets above there. I haven't heard anything in a tweeter even remotely as listenable in supertweeter duty as this Radian.
And yet, the human brain is a hungry beast. You could buy $500,000 speakers and if that Salvation is delivering information as well as you say, then even a half-mil will eventually leave you feeling you're not getting something you paid for in the source. Definition 4 will be a leap in musical realism for you. Enjoy your Def2s while you have them and have complete confidence in Def4. In the meantime, none of this is worth worrying over.
Phil
