I own both. The Benchmark LA4 is an excellent preamp and if you modify it to be powered by a quality LPS, an even better one. However, the Holo Serene Level 1 preamp in its stock form sounds better. It has a blacker background, the bass is cleaner and deeper, the transparency and detail is better and it has a warmth and musicality the Benchmark lacks. It did take about a month for the Holo to fully break in, so initially I had some doubts, but once fully broken in, it shined.
I did a test comparison against my friends Accuphase integrated(used as a preamp) when I first got it and then about a month later. In its unbroken in state, the Accuphase was the better sounding unit. It had more transparency, musicality and sense of realism. The only thing the Holo did better in the beginning was having a blacker background. The Accuphase has an excellent S/N of 117db but the Holo made it seem noisy. When I did a second comparison of the Holo to the Accuphase a month later, it matched the Accuphase in transparency, musicality, and realism and left it in the dust in background noise.
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