I did an abc comparison of the 521 BEE and the C542 by Nad and a California Audio unit. Unfortunately I can't remember the model of that one. It was one of the last ones they produced. I could definitely tell a difference between all three. The 542 is clearly better than the 521 BEE. There was no doubt to these ears.
The California Audio was very close to the C542. Very hard to hear any difference but once again clearly better than the 521. Your mileage may vary.
Sorry to put a gas reference in here.
oz
