I bought a nice used Garmin SL60 with rack and connectors on VAF classifieds months ago, and did a quick bench check after it arrived to ensure that it powered up and had basic functionality. I recently got to the point in my RV7 build where I'm assembling the panel and avionics. Unfortunately the audio for this unit was incredibly weak when I connected it to the audio panel and intercom. After trying another SL60 in the same rack, verifying my solder and crimp joints, changing antennas, checking other cables, I still had the same problem. Finally it dawned on me that the problem might be with the connector that was in the rack that came with the radio. A quick visual check revealed that the person who had installed wiring in the connectors (the unit included much of the wiring needed for connection to my audio panel, EFIS, etc.) used MALE ends rather than the FEMALE ends needed for that connector. I ended up replacing five or six crimped ends with the proper gender. Problem solved. Never ASSUME that the last guy who worked on your used avionics knew what he or she was doing. Doh!