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SAC's new top-line preamp—we reviewed the smaller Beta in the past—gets a completely new motherboard. Not only are traces twice as thick as the Alpha's, the entire layout has been rethought particularly for its ground plane. SAC boss Axel Schäfer comments: "The circuit board is an important element of any amplifier. It's critical to implement grounding such as to avoid all eddy currents so that the ground potential between input and output signal doesn't skew. How clean an amp works and how deeply one can listen into the music action is heavily influenced by the lack of signal overlay. Lots of copper helps. That's why our two-sided board runs 75µm traces on each side. To avoid impedance offsets all current-carrying traces are duplicated on the bottom. It's very important to avoid eddy currents in the signal path. Ground connections thus always proceed from the top to the bottom contacts."

Obviously SAC also paid attention to clean current delivery. Proof isn't merely the choice of external power supply which naturally suffers lower coupled radiation issues. The main unit too gets power filtering and stabilization. Incoming voltage from the PSU hits two 10.000µF filter caps followed by a current-compensated coil followed by another two 10.000µF caps whilst voltage regulators create pre-stabilized voltage as Schäfer put it.

Once delivered to its various circuit blocks of input, output and control logic stages, discrete regulation performs 'post stabilization'. The input stage shares a common ±15V supply flanked by 2 x 10.000µF. The output stage goes dual-mono with another 2 x 10.000µF buffer. Wondering how all of it affects the sound, one first needs to decide on which power supply to use. My answer didn't take long. The big one pretty please.

True, the €500 surcharge relative to the €3.500 core sticker with smaller PSU isn't irrelevant. But neither are the sonic gains. My notes put it thus: "Smaller power supply – somewhat sharper sibilants, tonally lighter/brighter, stage flatter and less sculpted. Big power supply – calmer blacker background, very sculpted, strong depth illumination, deeper firmer bass."

As always with this stuff, sonic difference are gradual rather than novel worlds. But still and particularly if the SAC preamp will be used with a transparent resolving system, I'd nearly call the bigger PSU mandatory. Otherwise you leave too much potential under the table. For my audition I exclusively used the big 'un. Let's go. To kick off with tonal balance, the SAC La Finezza was a golden example of neutrality and balance. Compared to my Octave HP300MkII one could think that the SAC had more going on in the bass and less in the treble and brilliance region. But that'd be more due to the Octave diverging from neutral in the bass. The deck from Essen plays it straight and sans preference in the amplitude domain.