Hey @FourT6and2 I am not really sure on which diodes I will use.. I am aiming for a more subtle diode clipping as I like the rawness of marshalls and its enough compression for what I play. Also I don't like to much of a voltage drop. This would need to incorporate a second master imo.
Maybe Ill try the same zeeners like in the Jose stealth mod video first and adjust from there:
That's a long video and I must have missed the part where he mentioned the diodes. But I do see MPSA06 transistors in the schematic. Those are one of my faves, but will clip a lot compared to higher value zeners. If you want subtle, I'd suggest not going lower than 18v zeners. And you can also throw some resistance in parallel to reduce their effect. There's a chapter about it in The Ultimate Tone books.
Actually, looking at the schematic closer, it's fairly close to the amp I built (clip in my signature).