Studio Preamp Differences

[RectoStudioGuy]

I've noticed that some Studio Pre's have different things about them than mine. EQ back ground color, metal toggle switch for loop rather than a rocker switch. Are the differences purely cosmetic or is there more to it?

 

[ytse_jam]

There should be two version of the Studio Preamp circuitry. In one the reverb driver (V5) is a 12AX7, in the other it is a 12AT7. I don't know if there is a relation such as:

metal toggle switch for loop, grey eq background color >> 12AX7 reverb driver
rocker switch for loop, dark eq background color >> 12AT7 reverb driver (jus like mine)

I suppose the difference in the circuitry is limited to the reverb section and shouldn't have a big impact on tone, but I never checked it out.