The red channel on the old 2 chan rectos DOES NOT have negative feedback, this is why they run a fake presence control, that is just a high cut filter after the tone stack. Only the orange channel has NFB. But of course you can set the orange chan to be high gain.
Anyhow your sound clips do sound very similar, you were clearly able to get it to sound like a SLO.
Personally I like the old 2 channel rectos better.