My Denon x4000 is on its way to Panurgy for warranty service. Meanwhile, I am using a 30 year old Carver m1.0t amp and a slightly newer Carver preamp. I am noticing significantly better imaging and a sense of "air" on minimal-miked recordings that was not so evident with the Denon. Transients are clearer. There seems to be less compression at louder volumes.
Since the Carver equipment has no DAC, I am running all of my sources (cable box, Roku, networked audio files) through my Oppo 103 player. I can't tell whether the improvements are due to the Carver equipment or the DAC in the Oppo. I doubt if the improvement is due simply to more wattage in the amp (rated 200 wpc), since my speakers aren't that demanding and are not getting played at deafening volumes.
So this will take some investigation when the AVR gets back.
AT&T U-Verse Northeast Ohio
Denon x4000, Carver m1.0t, Samsung LED TV, B&W 704 mains, two M&K subwoofers, Oppo 103, Roku 2, etc.
Headphone system: Sennheiser HD600, AKG K702, Hifiman HE-400i, Marantz HD-DAC1 (also used for music playback in the main system, Marantz CD5004, Denon DVD-3910