CJ ET-3 mods?

So I've got the ET-3 (NOT the SE version), and although it's the greatest rock'n'roll preamp I've ever heard, "neutral" it ain't...  The eBayer who sold it to me had an Electro-Harmonics Groove Tube in it, which I promptly replaced with a brand new Genelex Gold Lion.  Definitely cleaner, but...

The preamp has a "lit-from-within" sound to it, one that I associate with Nelson Pass power amp designs.  The treble is highlighted, and the midrange is too dynamic.  For example, when Norah Jones' voice comes in on "Come Away With Me," it's TOO present & edgy.  I previously had a McIntosh C-220 that did much better neutrality with the same Genelex Gold Lion tubes.

So I need to tone down the CJ.  First idea - Tube rolling.  I have on hand a Telefunken, an Electro Harmonics, and I have on order a Russian Voskhod tube.  Any idea of which might cool down the CJ sound?

If tube rolling doesn't neutralize the sound, my second guess is that the Teflon caps in the signal path may be upping the "perky" factor.  Perhaps replacing one or two with polypropylene equivalents might do the trick?

I see NOTHING anywhere on the internet about modding this preamp, so I'm assuming that the factory tube (whatever it was) is significantly more laid-back than my Gold Lion.  

Suggestions appreciated.  Thanks - Boomzilla (Moniker NOT indicative of listening preferences)