Why is this ARC so BIG physically when it only is a 600W amp, the transformer doesn't appear to be that large, which would be the important piece in teh entire power supply? There is a lot of free space in the cabinet too. I'm sure it needs air flow, but a well desinged chassis can be compact, with good air fow across the stuff, beside they have teh tubes on top where they belong for heat to leave. What would 4 of these in a room do to the temperature rise!!!! Eeessshhh. But it's horrible specs, lousy damping factor, with so much, it seems you get so little. Reminds me of teh early radio transmitters using tubes, they where gigantic, now replaced with SS in most stages, reduced heat and size. This thing is like a throwback, but it sure looks neat I guess, hardly "reference" as they like to tag it.