Sunfire Signature... what is this?

Not sure why you'd expect to hear much if any real difference. Most listening is at lower W's and very few peaks ever approach using all that headroom. As noted, the differences in your pre- and post-purchase amps is really kinda minimal (maybe 1.5dB if you could A/B 'em) so unless components have deteriorated and/or you're crankin' 'em all the way you'll likely have to imagine any big change.

Hmm.. ok, the reason I bought the 600 is that I had a 200x5 (C-1000), and although I didn't hear anything "wrong" with it, when I got the Cinema Grand 400x5 hooked up, there was a definite improvement (I know, different technology). So, I went with the "if more is better, still more is more better" philosophy.

It does make sense that there would be a point of diminishing returns. The 10-amp input, as Almarg notes, seems under-rated for 2x600w channels, and my speakers are 4-ohm (magnepan), so *could* pull 1200 watts each, which the amp wouldn't be able to supply for very long.

I hardly ever crank up the volume *really* high, but I again, at moderate levels, I hear an improvement between the
300w/ch C-1000 and 800w/ch Cinema Grand (into 4-ohms). I don't detect an improvement between the 800w and 1200w Sunfires, and maybe that's not to be expected, at moderate volume levels.

The "SS" mentioned by Rpfef appears at the end of the serial number, another clue that this is a Sunfire Signature.

I think I will send the amp to Rita's, and if I still hear no difference when I get it back, I'll figure out what to do, then. I'll have over $2k in it by then, and probably can't recover all of that, but I could then re-sell it with a clear conscience.

Thanks for the input. Great forum.

Your new amp is very powerful and is of a different design then most SS amps. It does indeed drive difficult loads with its rated power into 8 and all the way down to 2 ohms.

It drove my large and very difficult to drive Soundlab M1 speakers with absolute ease. It always ran cool also. To my ears it greatly surpassed the stock 300 watt stereo amp in my system.

Bill at Carver's authorized repair facility will do what is needed and go thru the entire amp with extraordinary care to every detail. My Sig 600 came back with an entire new right channel board, power supply caps and the voltage rails adjusted for maximum performance. He also replaced many caps with higher rated ones based on learnings over time.

I put an iec on mine and used a good quality aftermarket cord. All of these things really improved the sound to my ears on my SL speakers. I think it will be a keeper for you. I think it shares the same sized transformer for two channels as the transformer in that multi-channel home theatre Sig amp.

Doesn't the Sunfire amps have a feature for solid state sound or tube sound. I looked it up and it said, For those who prefer the crispness of solid state amplifiers, there is a voltage source output, and for tube sound, there is a current source output. You put it on which ever one sounds best for you.
Which one do people like the best?

Twilo, the manuals suggest that the current source is possibly better for planar and/or ribbon speakers, the voltage source for conventional cone-type drivers. For the magnepans, I prefer the current source. Some classical pieces will bring tears to your eyes, the sound is so poignant.

You can also bi-wire, if your speakers allow for it.

I think "best" would definitely depend on the speakers you're driving, and the material you're playing.