What's going on in this circuit?

[AlanInSitges]

Note: this probably belongs in some other forum but I feel more comfortable here so hopefully it's not too-too out of place. Besides, I inherited a tuner along with it so together they make a radio and that counts.

I've been looking at a schematic for an old integrated amp I inherited when I was a kid, and it seems like a pretty straightforward design, but there's something that seems out of place and that I don't understand: what are those two massive resistors doing around the cathodes of the output tubes (R48, R49)?

There is an earlier version of the amp that has the same big one from the screen to the cathode, but the second one from cathode back to the B+ isn't there.

If there are two resistors in that circuit dissipating nearly 30W I can't figure out where that much current is going.

Can anyone explain?

Thanks.