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Review Pass Labs X150.8 – Entry-level Pass… or is it?


  • Very loose character
  • Layering
  • Little or no colouring


  • You're 100% sure to tweak
  • Gets hot
  • What do the big brothers do?
  • Prijs: € 8750

    Build quality


    It started with a new dac... then a new power amplifier and now new speakers... What a journey. But anyway: it's fun and educational. This Pass Labs X150.8 has shown that the 'entry-level' is more than capable. It is a gem... a technically impressive piece of engineering. It measures well and sounds very good. Nice and loose, fast, clear, layered... pure. 100% definitely Alpha Approved... but that's no surprise. After all, it is now the Alpha Reference.

    Measurements and Conclusion


    We have of course measured the Pass Labs X150.8. Now we were curious what the burn-in process actually does, measuratively speaking. Are there any differences between a new and a burned-in sample? Well…. it seems that this is the case with these standard measurements. However, the differences are very small. And that can be within margin. We are talking about sometimes 0.001% difference. What is striking, however, is the THD vs Freq measurement. It really shows obvious differences. (overall just lower distortion) than new out of the box. And that is reproducible. We also get íttle more watts out of it (2 to 3 watts more).

    Measurements – new out of the box

    Measurements after 2 months of inspiring

    We can’t help but say that Nelson Pass has put together an excellent piece of electronics. Even with the low feedback we see a very quiet character and especially amplification with extremely low distortion. The frequency response is particularly straight up to about 70 kHz (-1dB). The power measurement shows that it measures very conservatively. We measure 154 watts at 0.2% THD and 280 – 290 watts into 4 Ohms at 1% THD. That is neat. Nice work.

    What strikes us is that the distortion is incredibly low in all measurements. Even at an input of 37 uV we see a THD below 1%. That indicates that Pass has its circuits well under control.

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