Arthursmuck...I have one, two ch. Signiture; but i will saw this...i went from 200 watts per. ch., to 600 watts per. ch. and the difference in sound is obvious at all volume levels, but it could be the design difference of the two amps. and not the added power or both.
Here is the other review i found>
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Randy Bingham at Sunfire urged me to try a second Sunfire Signature Amp in a vertical bi-wire configuration. This means you use two Sunfire Signature Amps. Each is fed an unbalanced signal to the normal input then the lab input for left and right are bridged with a single (mono) interconnect. If you bi-wire or tri-wire your speakers as in the case of my reference Cello Stradivari Legends, you should connect the high/mid leads to the current output while using the voltage output for the bass leads. Got it? Good. Don't worry it took me a minute to figure out too.
The best way I can describe the change in sound is to make a car analogy. I drive a six-cylinder VW GTI. It meets my budget and my need for speed which is a nice tradeoff. The difference a second Sunfire Signature Amp made is like trading in your GTI in on a Porsche 911. The extra power elevates the music to a whole other emotional level. Yes, I know there is an extra $3000 plus an interconnect included in the price of this upgrade, however it is worth it. And who said you ever had to buy it all at once?
The sound of the vertical bi-wired Sunfire Signature Amps multiplied everything good about the sound of the amps. The best test for the effect of the second amp was using the new MCA remasters of Jimi Hendrix's Axis Bold as Love. On "Little Wing," Jimi's guitar floated in space, something I have heard in few systems. The power of these amps was frightening. I don't believe in inefficient loudspeakers. I like my Cello's, WATT's and Puppies and even slightly less efficient transducers like THIELs and Martin Logans, yet these Sunfire Signature Amps feel like they can drive any difficult load from Apogee Grands to a Lincoln Town Car.
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