I just picked up a used Zen 84C and have a few questions about it.  I changed out the tubes to NOS and am loving it right now .

My amp says it was manufactured in 2005, serial number 608,  though when I opened the amp it has a date on a little block of wood of 2007 signed S.D. And I assume that is Steve Correct?  On the outside of the amp it says SE 84C EX (the EX is in a different color and I am assuming that Steve added it in 2007.).

I was going inside to see how many and what size caps I would need and there are many caps inside.  Two pairs that say 0.33 and a few others in a larger size.

The question I have is:
1. Should I just send this amp to Steve for the V Cap upgrade and the Hazen Grid Mod all together?  
2.  What does the EX lettering mean?  
3.  How close sonically is this unit to current production?  
4.  Any idea on cost for this level of upgrade with the Mod and the V Caps?

Thanks

So since I have 8 Ohm speakers with a crossover, albeit a small crossover, At 98 dB Sensivity, the EX mod would not be in my best interest correct?  

I have noticed in certain passages a bit of distortion at moderately high volumes, though not at the volume where clipping is occurring.  I'm assuming this is due to this mod?  I originally thought it was due to bad tubes as it has gotten a lot better with a change to different tubes....and may have disappeared all together.....hmmmmmmm