Wavetrader - My reported observations were relative. There are no absolutes here. When we upgrade a link in the chain, we are often overwhelmed with the new degree of refinement over what we had before. And until that event, we were fairly certain our system had outstanding tonal coherency, dynamic contrasts, portrayal of space, incredible resolution, etc. And then along comes one change, whether a cable, a preamp, a small-signal tube, etc., and then we are aware of what we had been missing from our great system of before.
When I first was exposed to NBS, first the Master and then a full system of Statement, I was a happy camper. I was not aware of its shortcomings because of what it did like no other cables that I had heard before. But years later, through encouragement by audio buddies, I tried some other cables and was quite floored by the flaws in the NBS. A direct comparison of the ICs and PCs made we well aware of what my system was truly capable of.
As for dynamic contrasts, this along with bloom have been the two things I have chased for 20+ years. The ARC SP-10 was the preamp that reigned supreme in both of these categories when it came out. And I have sought refinements here ever since.
Concerning tube amps that excel with dynamic contrasts, I have not heard the VACs, but after hearing the CAT vs Atmasphere amps 4 years ago, the performance of the CAT here was so far beyond that of the Atmasphere (which is a phenomenal product on its own), I seriously doubt that the CAT has any peers in this regard. This greatly influenced me to purchase the CAT.
We can be content with what we have but part of the experience is what we learn when we try something else or when a friend brings over a cable or a tube and drops it into our system. The danger is that once we hear this new level of performance it is mighty tough to return to what our reference had been before.