Splitting the power tube cathodes

[Bionic_Bigfoot]

I've heard that by splitting the power tubes on the 18 watt, the amp will sound more "open". Can anyone comment on what the advantages/disadvantages of the mod would be? I realize that if the cathodes are split, the components that the cathode resistor and capacitor used for each tube must be of twice the value of that which was used for both tubes non-split.

[colossal]

No disadvantages, save an added part. A bonus might be that you don't have to used matched tubes, but I would not let the mismatch (if any) be too large. I have tried it and liked the results. "Openess" is what I like too. I think I used 330R on each cathode to keep the bias voltage the same.