Linn uses (an excellent) switch mode power supply, thus no need for the massively heavy torroidal power supplies you find in most higher end amps. (Dynavector also uses a switch mode power supply in their gear that may be even better than Linn's.)
Some people are psychologically attached to massive amps. I personally am not - what matters is how the thing sounds. I also actually prefer my audio gear to be manageable in size. It makes placement more flexible, makes it much easier to work with (e.g., switching out components for A/B's), and has much higher WAF. I don't think I would have a prayer of having my gear in the living room if I were using something like Levinson or Krell.