This wasn't the first time you played through a preamped Fender twin/DSR ? I have to say I can't live without mine. I use to use a Mosvalve SS amp and moved to the Mac and noticed a great degree of warmth returned using that amp. Pretty cool experiment, and at a gig no less.
I want to get a Mac at some point. I haven't seen one blatently pass before my field of vision yet, nor purposely hunted one down (yet).
Because I have my other Head (Vibrosonic Reverb) modded to Waldo's JG TR spec, I have been using it (I too often run it with just the outer pair of tubes, this makes it want to see 16ohms though... A DSR with only two tubes would want to see an 8ohm load).
This was actually the first time gigging with the DSR, although I had it up and running at home since I got it (I had the power cord replaced to 3-prong like the day after I got it, besides that, no mods other than the pre-existing pre-amp tap).
The other side of the story is...
I strained my freakin' right Bisept muscle lifting the DSR!
It fuckin' still hurts!
Now I want that light two space rack with a SMS JG Pre and a Velocity 300!
This was an un-mic'd gig in a place where it's possible to be too loud with a Twin Reverb style combo amp (The White Eagle here in Portland).
I was thinking with the SS amp around 2 o'clock was pretty similar to the DSR power output, and was trying the mix & match thing with the speaker outputs.