API 527 ($895)

API is one of those companies whose name brings words like “vintage,” “analog,” and “quality” to mind. So suffice it to say we were excited to discover the 527, a 500 Series module that offers a single channel of VCA-type compression of a similar type to what''s found in API''s 225L compressor and its 2500 stereo bus compressor. It gives you knobs for ratio, attack/release, threshold, and output. You also get switches for knee (hard or soft), meter status (output level or gain reduction), and stereo link. You can also flick a switch to turn on API''s patented Thrust circuitry, which applies a sidechain filter designed to preserve low-end punch on heavily compressed sources. Another switch lets you choose between New (feed-forward) and Old (feedback) VCA functionality; the former provides transparent compression while the latter squashes with more obvious color. Our reviewer tried the 527 on a variety of sources, including kick drum, bass guitar, and electric guitar, and was impressed with both the unit''s sound quality and versatility.