Rogue Audio Dark Upgrade.

That upgrade is $$  and shipping damages are always possible not to mention $$

Id say maybe conciser Some excellent NOS Input tubes and have a tech install some Sweet Coupling caps

Good reading

Please Click                       " Capacitor Check"

In the last link for a good read

@mulveling thank you 1st and foremost with your experience and recommendations.  I have a ST-100 and wondered exactly what you brought up. Would I even like the upgraded caps. Caps probably make a big difference but which one would be preferred. Hiend2 also brings up a good point and that is to purchase caps and have a tech install but again which ones?  In addition,  shipping back and forth isn't cheap plus the possibility of damages if shipped to Rogue for the Dark Upgrade. 

NOS tubes are another recommendation but which 12AX7 are considered popular for the ST-100?  I have several 12au7 to experiment with.  I  prefer a neutral to slightly warm sound. 

Lastly, the only downside of changing caps is it could hurt resale value because some buyers do not want to purchase a modified component unless it was performed by the factory. 

Throw some VH Audio ODAMS in that amp.

I’ve been mulling whether to send in my Rogue Stereo 100 for the "dark" upgrade, but seems to really not be worth it. I already have good tubes in the ST100. After many combos having found CBS 7729 (gain) 7730 (driver) to be fantastic. More punch and equal clarity to the long plates Amperex and 7316 I had in there. I’ve also tried Telefunken 12AX7s and multiple other tubes, and to me the CBSs trump them all, once the 7729 broke in (There seemed to be some grain in treble that is gone now). That was a nice tube surprise! Rogue will charge $~1350 for the upgrade sans tubes and $1500 with their choice of Telefunken and the like. On another note, I’ve recently sent in my Rogue RP7 for upgrading to RP9 and am VERY happy about the change.