Pulse Techniques recently introduced a 500-series version (EQP-500X) of our popular 19″ rack-mount solid-state line amp program equalisers (EQP-1A3-SS & EQP-1S3-SS) equalisers. Based on the venerable API 2520 op-amp followed by a high-quality Triad output transformer, these are preferred by some engineers to the vacuum tube models.