Tweeter Capacitor Upgrade (Coincident PREs)

Have you thought about using paper in oil caps?

I am partial to the Jupiter Copper Foil.
To me the Audyn True Copper can be just a little tilted in the upper mids.
The Jupiter Copper Foil paper and wax is my Favorite,although not cheap
http://www.soniccraft.com/index.php/jupiter-copper-c-301_38_416

Another vote for Jupiter.

Geta2ay from plastics like a Mundorf s ownedtheir Best Silver Gold oil supremes several times . TheJupiter Copper foil 
muc more natural and meaty once you give them 300 hours,
and a Duelund. Silver foil ,oil.01 Bypass cap really opens the top up . Solen is junk,  depending on budget .
go to humblehomemadehifi capacitor test.   A solid A recommendation I usethem myself in my speakers .whileyou are 
at it rebuild the whole Xover austral bloom uses Nothing 
remotelyhigh quality .i owned several  amps speakersall economy 
parts .I modded them  myself , a Huge difference , and for suerewire them , I just used VH Audio New AWG 21 for the tweeter, awg15  forthe other drivers a Litz ssmall diameter 
OCC - 0 crystalCopper verythinned foamed Teflon dielectric  
fantastic wire . He sells a awg 12 and awg 11 forLoudspeaker cables, and use Copper get rid of the junk brass ,on the terminals 
not natural stall I changed every connection throughout to copper
at lesst a 10% improvement . I used the exsctwiring for my amp-preamp, Loudspeakers also. The whole system .time consuming and maybe $1500 in wire but the results are substantial.

i think isreal uses his top of the line statement cabling inside throughout for his PRE i dont think youd need to upgrade the wiring inside. dont know about the caps.