I think the new Jolida KT150 based amps are the fancy new two piece mono amps. Ditto on the Jolida 502p...I went in casually with no regard for terrifying heater supply disasters with KT120s and they lasted almost 3 years under hard use, sounding great (rig dependent maybe...but friggin' great). The KT150s I replaced them with have been tootling (audio term...meaning "to tootle") along perfectly for nearly 4 months and sound fabulous...I bias 'em at 500 as that's easier, and I'm not smart enough to know why 700 is better...in any case, note that relative to what the competition charges for tube amps, you could buy two 502ps and run 'em in mono if you thought you needed more heat in your listening area...but note that the factory modded 502s remain a nearly unchallenged bargain as a quiet running powerhouse of glass based electron manipulation.