In the world of high-end audio, some products don’t just fade away—they become benchmarks. The original STAX SR-009 was exactly that. For over a decade, it was the gold standard for transparency.
With the recent announcement of the SR-009D in December 2025, STAX has done something rare: they’ve brought back the soul of the original flagship while fixing every "quality of life" issue that users complained about for years.
Here is how the new SR-009D differs from its ancestor.
1. Release Timeline & Positioning
-
SR-009 (2011): The original king. It was the ultra-premium flagship of its time, designed to push the limits of what a circular electrostatic driver could do.
- SR-009D (Late 2025): Released as a "Revival" model. It sits in a unique spot in the current STAX lineup—offering flagship-tier sound at a more accessible price point (approximately $2,890 USD) compared to the SR-X9000 or even the SR-009S.
2. The Core Tech: MLER vs. Refined MLER
Both headphones utilize MLER (Multi-Layer ElectRodes) technology, which uses photo-etched metal plates bonded at the atomic level.
- The Original: The SR-009 introduced MLER, providing a level of speed and "see-through" clarity that was unheard of at the time.
- The SR-009D: It retains the core MLER architecture but benefits from 15 years of manufacturing refinements. While it avoids the gold-plating of the SR-009S (to keep costs lower), the "D" model uses a refined version of the original stainless steel plates to maintain that classic, lightning-fast 009 sound signature.
3. Key Feature: The Detachable Cable
- The "D" in SR-009D might as well stand for "Detachable." * SR-009: Had a fixed, non-removable cable. If the cable snagged or failed, it meant a costly and stressful trip to a service center.
4. Build & Comfort: The "Weight Loss" Program
One of the most significant physical changes is the housing material.
-
SR-009: Utilized a heavy, all-aluminum frame. While premium, it contributed to a heavier overall weight.
-
SR-009D: Incorporates a newly developed injection-molded unit case. This high-tech material significantly reduces the weight (down to roughly 452g without cable), making long listening sessions much more comfortable.
- Adjustment: The "D" model also inherits the 10-step click mechanism for the headband, allowing for a much more precise and repeatable fit than the older sliding friction design.