I personally like to split the cathodes of the first tube, when doing this remember, on the cathode with the 22uF cap, to up that resistor value to 1k5 from the 820ohm... on the other cathode, you could try either a 1k5 or 2k7 resistor and a smaller cap, say .68uF or 1uf... I also like to change the coupling cap on that stage to something smaller, like either a .022 or a .0047u cap. The amp will have a bit more chime on that channel, and when you bridge channels, the tone gets reaaaalll thick...