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.
Sunfire Signature... what is this?
Recently bought a Sunfire Signature amp, believing I was getting the 600x2 model. The front panel has "Sunfire" above the Joules meter, and "Load Invariant High Fidelity Stereo Power Amplifier" below. A Bob Carver signature is on the upper left of the panel. The rear panel has "Sunfire Signature" just above the serial number (which starts with 99), and a lot of the other normal printing. The two speaker fuses are labeled "5 Amp SLO-BLO MDL/Q", and the AC line fuse is labeled "10 AMP MDA-10 120 VAC", which makes me question if this is a Sig-600. Any thoughts?