Just an idea I have percolating. Rather than multiple tweaks I wanted one switch to change the nature of the sound of an amp. Or two switches, we will see. The main alteration would be to change the phase inverter from a Long Tail Pair to a Paraphase inverter. I might put in a pot to dial in the balance (or imbalance of it) or find a resistor value I like and call it a day. Along with that the first stage is changed from cathode biased to grid leak. To top it off would be to change the output fixed bias to cathode biased to loosen up the sound and shave some voltage across the output stage. Also loose the negative feedback. It would be nice to switch in some sag in the power supply but the four poles of the toggle switch are used up. Again, subject to change but a possibility. Hopefully getting a more 5D3 vibe or tightening everything up for a Blackface response. Which brings up the tone stack. The double pole switch can change from a scooped sound to more of a Bassman/Marshall response. The use of a three position, center off give three different flavors. Whether I go for an extra switch or just two positions with maybe the treble switch with a push-pull switch, we will see. I need to finish an amp for someone else so this will be on the back burner for now. But it is something I thought might be presented for your enjoyment.