Anyone listen to Zu Audio's Definition Mk3?

So you like the Def IVs?  Hurricane Sandy, with all the electric surges, killed one of my Def 1.5 amps-- Perfect rationale to explore updating or fixing the blown amp. I was going to post, but reading your( as usual) eloquent listening experiences with the Def IVs is giving me more than a mere itch. Were (I downloaded the manual) the speakers hard to tune? After living with these babies for a year, do you have any new info about the IVs? You were my inspiration for the 1.5s, so I’m beholding. Having a wonderful SET amp and pre with NOS tubes will bring out the best in the IVs. Now all I have to do is convince my wife. This is going to be a very difficult sell for me waiting on delivery of an (much harder sell) environmentally unfriendly naturally aspirated 8 cylinder….ooh I get the chills, but let’s stay with audio..

Also:
How do (2) 12” down firing woofers compete with (8) 10 inch rear firing woofers? One of the many things I love about my 1.5s is the prodigious, window shattering bass, when summoned, raises the hairs on my neck. The bass, however, was never as taught and punchy as I would have liked. Jazz, however, was always wonderful. I accepted this as a characteristic of tubes. Do the IVs feel like they are moving as much air as the 1.5s?

I cannot compare the Def 4s to the Def 1.5s; but compared to the Def 2s, the Def 4s have bass that is both more taught and more visceral.

Charles, the 6Moons preview of the Druid V makes special mention of possible upgrading in SQ by substituting caps, from the stock Clarity Cap, thru the Intertechnik Audyn Copper to the Duelund Black. Consensus was that the Duelund is the way to go, although the Audyn well outperformed the stock cap. Really feeling this is the next place to go re upgrading.
Is the Duelund Black the same as your Duelund Cast Copper?

Spirit,
Here`s the pecking order.
1)CAST, Silver foil(uber expensive!)
2)CAST, copper foil(expensuve)
3)VSF Black, Silver or copper
4)VSF, Silver or copper
5)Alexander, entry level
Given the cost of your Zu DEF IV. and the level and cost of your system, I`d go with the CAST copper and be done with it. No 2nd guessing, CAST are made for high caliber systems,get the best.My Coincident speaker is very good but the CAST simply raises it to a higher performance level. You won`t regret this capacitor improvement.
Regards,