Does anyone have opinions of the Harman Kardon Signature 1.5 and 2.1 amps? www.jandr.com has the refurbished 2.1 for $499. I'm thinking of replacing my Adcom GFA-6000 with the 2.1. I like the fact that it has a 12V trigger for power on and it will match my new Signature 2.0 pre amp. Would it be an upgrade, downgrade or lateral move in terms of quality compared to the Adcom?