The original Musical Fidelity A1 integrated amp has been something of a classic ever since it was first released in 1984. Designed by Tim Paravicini (now at EAR), it is almost entirely Class-A in operation, it has a low distortion and warm character to its sound. However at just 20W output per channel, speaker choice is severely limited.
Released in 1986, the A100-X steps in to overcome these short comings, with beefed up transformer to deliver 55W a channel and still highly biased to class-A (although not as much as the A1). Heat dissipation is even bigger a problem than on the A1, hence the A100-X employs internal fans to actively cool itself, blowing heat out of the side panels.
The A100-X shares the same output transistors and phono stage as the A1, and thus shares very much the same character of sound. The A100-X is much rarely than the A1, so don’t miss this one.
Another one has hit the market: