Vertex AQ, well-known purveyors of RF and microphony-busting devices to the discerning audiophile, doesn’t have quite the same traction in personal audio circles, but with the creation of its sister JSA brand, that looks set to change.
Currently, JSA has just two models in its line-up; the Type 1 and Type 2 Passive headphone conditioners with suggestions of a headphone amp to follow. We got the Type 2, with high-grade cotton insulated solid-core silver wiring, a labyrinth construction suggested to reduce microphony and vibration transmission, and a combination of Vertex AQ’s best EM and RF interference absorption devices. The cheaper, cut down Type 1 is 60cm shorter and a kilo lighter. There are optional more up-market input jack cables featuring the same solid core silver wiring in 0.6m and 1m lengths, which we also received.
The JSA is about as straightforward as it gets in terms of installation. There are two ¼” TRS stereo jack sockets – you plug the male-to-male input jack cable into one, you plug the other end of that cable into your headphone amplifier, then plug your headphones into the remaining socket on the JSA. That’s it. You could spend weeks fussing over which jack socket sounds better to the headphone, and which sounds better to the amp, and conclude it makes no difference. It’s a purely passive conditioner block.
There are two ways of testing this. The wrong way is to act like a 1920s telephone operator, moving jack plugs in and out and performing quick-fire AB comparisons. You will hear a difference, but may not be able to ascertain what that difference is, why the difference counts, and ultimately whether your headphones are materially better with the JSA ‘in’ or ‘out’. Instead, treat it as if it is a permanent fixture to your headphone listening for a week or two, then remove it and see whether you can live without it. Chances are, you can’t.