Even though it's all op-amps, I can vouch from experience that the preamp in these pictures is one fine piece of gear. Very clean and plenty of headroom.
My guess in the IC's are Analog Devices AD797 or Burr Brown OPA627/2604s just because of the specs of those op amps. Also, I doubt Millennia would go to any trouble to hide the identity of a 5532/34 chip! That would hardly make for a good secret weapon!
You could measure the voltage rails on the chips, and if it's more than +/-18v that would rule out the AD797 chips, although it is my belief that they are probably the most linear and quiet of all the chips I have used.
I like the OPA627/2604 chips too, but from knowing the Millennia's sound I can't imagine it being them. The Burr Browns always sound darker and fatter in the low end in the instances I have heard them. The AD chips sound just like my Millennia, in my MP20 (which has a transformer input howerever), so that's why I suspect those.
The MP20 runs the AD797s at +/-18v though (they are listed as +/- 15v with +/-18 being the absolut max), and they sound superb. I was thinking of slapping a small heatsink on each chip (do you gurus think that's necessary). The MP20 has proven to be the only pre for some jobs. Most recently it was nylon classical guitar. It was the most accurate of the bunch (312s, 1272s, HV3, and MP20).
Shane
