The Pre Box S3 mostly ignores that rule. Pricing is set at $699 (£499 / €599), positioning the Pre Box S3 as a mid-priced option for a compact preamplifier that also covers DAC and headphone duties in one unit. Pro-Ject Pre Box S3: A Compact Hub for Modern Audio SystemsThis is a do-it-right, don’t-show-off design. The Bottom LineThe Pro-Ject Pre Box S3 is a compact control center that focuses on doing the essentials properly. Designed as a natural partner for Pro-Ject’s Amp Box S3 or Amp Box DS2 when more power is required, it also works just as well with other power amplifiers or active speakers.