Modular, over the last 20 years I've listened to a broad range of amps in my system (some bought, some borrowed). Everything from Krell, Rogue, CJ (tube and FET), Quicksilver, Melos, Rowland, NYAL Moscode (!), White Audio (!), Bryston, to Adcom, APT, VAC, and Bedini, which turned out to be my amp of choice for the last 16 years (even with all these others getting switched in and out). All this through the same preamp and speakers, in the same room. It's only recently that I joined those who own FetValve amps (even though my closest audio friend has been running with a 350HC for the last 10 years). The EXR convinced me to switch out my trusted amp of 16 years; overall it is better than my old Bedini, and all the others I've listened to over the years. But... it does have very small areas where it might be a bit better. Which amps did what better? The Krell, Bryston, and Bedini had *slightly* better low end articulation; the Quicksilver has better transparency, but none of these did all things comprehensively as well as the FetValve.
But, please note that in this world of audiophile over-differentiation that we are in, my comments relative to the FetValve are MINOR, at best. I wouldn't have switched out to a FetValve if I wasn't overwhelmingly pleased and satisfied with what it does. I bought it planning to keep it unchanged (hopefully) for as long as my old amp. The Ultra is a tempting lure, but my hope is that it does the EXR better without changing its fundamental character. Seeker's comments begin to bear that out.