Audiophilepure

https://www.stereophile.com/content/dan-dagostino-master-audio-systems-progression-m550-monoblock-power-amplifier

Following late-night phone consultations with Editor Jim Austin, I awoke to speak with Bill and Dan about the possibility of delaying the review and sending the amps back to Arizona for repair. Dan, though, was certain that the amps were fundamentally sound. He thought the discrepancy was caused by a shift in biasing, which presumably happened during shipment.

Two tension-fraught days later, Hans Brackmann, Definitive Audio’s store manager, drove to Port Townsend to rebias the amps. All D’Agostino dealers are prepared to rebias the M550s whenever necessary.

Sure enough, rebiasing was called for—just that, nothing more. By the time Hans left, both channels sounded the same (save for minor discrepancies caused by room imbalances), and I heard even more of the beautiful, smooth, finely detailed, impeccably controlled, remarkably dynamic, slightly warm and glowing sound that had made me fall in love with the Progression M550s.

My listening room was designed from the start to provide a fairly close approximation of the Cardas Golden ratio, and was wired with dedicated outlets for the audio stack. I’ve since upgraded the setup with AudioQuest Edison NRG power outlets, and with the other AudioQuest Niagara equipment that I’ve been able to add, I’ve achieved an incredible level of quietness within my room and system. So I can easily discern any electronic hum or buzz coming from any particular piece of equipment within the room. A very slight hum emanated from each piece of the Wells Audio equipment that was clearly audible when standing near them, but was much less obvious from my listening position, which is about 18 feet from the equipment stack. During operation, no noticeable noise was present in the audio spectrum with either analog or digital sources. 

I run the LRS loudspeakers full range with a pair of subwoofers, a REL T1 and a Definitive Technologies Powerfield 1500, with no crossover employed between the loudspeakers and subs. Over the two years the LRS has been in my system, I’ve gotten the sub placement and levels dialed in to the point that playback is absolutely seamless with any musical genre. The LRS has the uncanny ability to produce shockingly loud SPLs with music that pushes levels that approach total realism for orchestral and even rock music. Which is completely surprising, especially for such a seemingly fragile technology that employs aluminum foil that’s glued to a mylar substrate. I’m pretty convinced that providing a great, high current amplified signal to the LRS is the key to getting perfect musical performance.

https://www.hifinews.com/content/bat-vk-3500-integrated-amplifier

The more time I spent with the VK-3500, the more strings I found to its bow. When fed some modern, techy electronica (and even with a regular-sized standmount), the impression is that it wouldn’t be out of place doing front-end duty in a nightclub. Paul Oakenfold’s ‘Save The Last Trance For Me’ [A Lively Mind; Perfecto PERCD003] came straight out the gate at full-throttle, a pounding drum track underneath waves of reverberant synths. Yet this slab of euphoria was peppered with surprisingly delicate touches, such as an isolated high-pitch woodblock that echoed serenely right

And with a track where bass is less prominent, the VK-3500 is able to shift gear easily. Through the big Paradigm Founder 100F loudspeakers, the sustained organ notes, soft strings and falsetto vocals of ‘Pause’, by multi-instrumental outfit Emily Barker & The Red Clay Halo [Almanac; Everyone Sang; 88.2kHz/24-bit], were painted in varying subtle shades. The recording was utterly spine-tingling.