Vac Sig MKII tube circuit upgrade

Interesting. I recently purchased a Renaissance 2 preamp on Agon and sent it in to VAC for just this upgrade. The Ren2 is a very similar circuit as the Sig2 (both transformer coupled), but the Ren2 does use the circuit board. VAC also added the ability to add resistors into the MC circuit to change the loading (accessible by resistor receptacles on the board)and upgraded some of the wiring and grounding to be consistent with the newer Sig2. I was really impressed with their customer service. The updated Ren2 originally blew me away ("I didn't know my system could do all of that!"), but I'm now feeling it's a bit forward/aggressive in the mids. Brent at VAC told me that the Ren2 is more forward in the mids than the Sig2. I only have about 30 hours on it since the upgrade, so there may need to be more breakin. And I haven't tried anything but the stock tubes yet (I've been too busy).

Interested in hearing the experience of others. Particularly how much tube rolling can vary the sound on the Ren2 or Sig2.

Thanks, Peter

I'm not aware of an upgrade to the Sig. 2A, his website does not say there is an upgrade as well.

I believe just the MKII as the IIA has that tube swap option installed already.

I believe Drummermitchell is right about this.

04-11-12: Drummermitchell
I believe just the MKII as the IIA has that tube swap option installed already.
Drummermitchell (Threads | Answers | This Thread)

Not true. Only the later Sig MKIIa has the tube swap option. I ordered my Sig MKIIa in mid 2011 and it has the option.

I spoke with Kevin and there's no circuit change, just a switch out of the signal path to deliver 6.3 or 12.6 volts depending on the tube type.