Of those amps, it would be between the 400MKII and the Forte 4A. I'd go with the 400MKII, which was a fine amp in its day and is still one of the better solid-state amps. If you don't need 200 watts per channel, the Forte 4A would also be a good choice, but the ARC will give you better bass extension and a more effortless presentation with virtually no drawbacks. The Aragon isn't nearly as refined as the Forte or the ARC 400MKII. I've never heard the D300, but the ARC dealers I know weren't all that impressed with it.
2 responses Add your response