RM seem to use whatever they can buy at the right price at the time, jumping from 1446 to 455 then back again several times over the years,
They did do a run with the larger 1051's some time back in the millennium amps and some kl amps,
you never know what will be inside until you look,
on full tilt FM the 4x1446 amps draw 40A+ @300w+ FM and the fuse holders melt if you get long winded, @34A you won't see anything like the output they claim,
RM should have used 4 fuse holders and 5w feedback resistors in the KL amps like they do in the HLA amps.
RM's V fan setup is total CRAP especially so on the KL800/805's with farty little fans fighting each other,
a single 120mm fan on the none V versions gives MUCH better cooling.