I set up the 4200SE in a pretty common configuration for a 4-channel amp: I ran the front channels in stereo to my full range speakers, and the rear channels were bridged to a high-quality 4-ohm subwoofer in a sealed enclosure. I listened to a variety of my favorite SQ discs and a couple of recordings that I mastered myself in another life. In every case, the Arc Audio amplifier performed with all the excellence I expected from a product with this pedigree. I listened to many discs over the course of nearly five hours. Yeah, I love my job!
The following are a few comments I jotted down while listening:
The vocals and plucked strings on Marc Cohn's "Perfect Love" were smooth and airy, with a good sense of space. Equal in this respect to my studio reference amplifier.
Blues Traveler's "Run Around" has a lot of complex kick drum work and some easily missed detail in those rhythms, but the Arc Audio amp had no problems reproducing the detail and the very low-frequency stuff that is not apparent on amps with some roll off in the lower end.
On bass-heavy recordings, like the Pussycat Dolls "Don't Cha," the amp showed no signs of stress, effortlessly playing the track as loud as I'd care to go. A common problem and one I'm always determined to check for in a configuration like this is the woofer "using up" energy needed to drive the mids and highs. No worries here!
Antonio Vivaldi's "Flute Concerto in D" sounded great, all the articulation and dynamics that the recording has were reproduced faithfully. Again, the 4200SE matched my studio amp, note for note.
The Gypsy Kings have a very unique sound with their expertly played acoustic guitars, the resonances of the individual guitar bodies were easy to hear... this isn't always the case with lesser amps. Another multi-channel amp I used for comparison purposes was very obviously not able to capture this detail.
On popular music, from Linkin Park to Maroon 5, the Arc Audio amp handled everything I played, with very good transparency and a neutral sound. It did what any good amp does, take the original signal and make it louder without noticeably adding or subtracting anything from the original sonics.