Sorlowski,
I'm not sure which caps you have in your preamp. My Chardonnay had the stock cap Mick was using about two years ago. He then told me that he found the Auricaps to be better. I installed them. They were better. (I am hesitant to point you to the specific caps as your unit may be different than mine, but they are the output caps off of the tube sockets in my unit).
However, after reading opinions about the Mundorfs vs. Auricaps, the Mundorfs seemed clearly the superior cap. I tried them. Sure enough, they were considerably better than the Auricaps. The Auricaps were fuzzy by comparison.
I had read rave reviews about the V-Caps for some time. I finally decided to try them. They are huge improvement over the Mundorfs and on another planet from the Auricaps. Simply do a search. With only one exception I can find, everyone seems to agree the V-Cap is simply in another different league than any other cap. It certainly is in my experience. And if you read the reviews from a number of highly regarded manufacturers, the V-Caps have no equal.
Regarding your question, which is better - the DACT or V-Caps. Hard to say. I installed the DACT long ago. Had I installed the V-Caps first, the DACT may have made as much difference as the V-Caps, but in the order that I installed them the V-caps made an amazing difference. I honestly believe based on other component upgrades I have made, the V-Caps alone made more difference than a $7,000 component upgrade I made about two years ago.
Amandarae, the V-Caps significantly improved the tonality of my unit, especially the piano. Not to mention the overall clarity. But I can understand your reluctance to change your unit. The Supratek in stock form is terrific, but I feel like my unit is so much better now it's not funny. Remember that Mick has to weigh parts selection based on a target price point of a particular unit. Using a DACT and V-Caps in a Chardonnay would probably increase the price of the unit by $600-$700 (with mark-up) if not more. But IMHO, the product can be improved if one is willing to spend the money.
Having said all that, in the end you may prefer a stock unit over an upgraded unit, but my ears tell me it's no contest. And just to give you a frame of reference, I prefer the cleanest, most transparent, detailed and tonally accurate preamp I can get. I am much closer to that now than I was with a stock unit.