Country of Origin



Reviewer: Glen Wagenknecht
Financial interests: click here
Review component retail price: €3'500

The S class of class D?

That's how SOtM as South Korea's Soul Of the Music might hope we will come to think of their new sPA-1000 amplifier. It just entered their catalogue's Ultimate range and is proudly bespoke, thus not reliant on an OEM module from the usual suspects like Anaview, Hypex, ICEpower, Pascal, Powersoft, Purifi or Texas Instruments. Like Tom O'Brien of Cherry Amps or Merrill Wettasinghe of Merrill Audio, Il Won Lee of SOtM penned his own switching output stage. At 7.5kg, his result is typically lightweight and packs into their usual 36x84x25cm full-size silver or black case with floating lid. At 100wpc/8Ω, it simply makes half the power of competitors which do 200wpc.

Where SOtM claim exceptional status is for power stabilization. Theirs isolates a balanced/bridged circuit from the 'pumping' effects of a speaker's back electromotive force on the feedback loop. Their specs call it active power supply noise cancellation with high-precision power regulation. By mid November when the company's May Park solicited me for this review, the specs didn't yet tell us much more than 10kΩ input impedance on both XLR and RCA, bandwidth of 20Hz-40kHz and THD+N as 0.05%. S/NR, dynamic range and input sensitivity still listed as TBD. The UK importer's website already had "closed-loop control for best THD performance and a 4th-order low-pass filter".

The online owner's manual already had this about the rear-mounted 'option' slider switch: "When the product is operating, it may affect AM radio reception. If that's the case, set this switch to 'off' to improve reception. When not in use, set to 'on'." Amplitude-modulated radio carrier frequencies live above the FM bands. SOtM's amp seemed able to interfere with the 535-1'605kHz band? That and far more warranted additional information. At this point Canadian contributor Glen checked in. He too had been solicited for the same assignment. Given his reliance on class D amplifiers for his main system, we decided that he'd be best equipped to handle SOtM's request. This is where the Irish editor bows out and the Canadian reviewer will take over.

… to be continued…