STAX SRM-500T Review
When it comes to high-end electrostatic headphone amplification, the STAX SRM-500T vacuum tube driver unit sets a new benchmark. As the long-awaited successor to the SRM-006tS—representing the first complete model change in 11 years—this hybrid FET+tube amplifier delivers exceptional clarity, warmth and dynamic finesse. Read on for our in-depth review, discover who will benefit most, and find out how to speak with our team at The Audio Tailor about securing yours.

Design & Build Quality

The SRM-500T maintains STAX’s signature minimalist aesthetic while embracing a new hybrid chassis that uses non-magnetic aluminium to suppress microphonic vibrations and external noise. The redesigned power transformer now includes dedicated low-voltage windings, improving power-supply efficiency and reducing overall consumption to just 38W. At 195mm wide, 376mm deep and weighing a mere 3.4kg, it’s surprisingly compact for a vacuum tube driver unit—perfect for desktop or rack installation.

• Hybrid FET + 6FQ7 / 6CG7 vacuum tube output stage
• Custom low-noise dual FET first stage
• Rigid, non-magnetic aluminium chassis
• Concentric dual volume knob and RCA parallel output

Sound Signature & Performance

Plugged into STAX’s advanced Lambda headphones (SR-L300, SR-L500 MK2 or SR-L700 MK2), the SRM-500T offers a frequency response from DC up to 90kHz. Its full DC-coupled circuit—completely free of coupling capacitors—yields an ultra-transparent signal path, preserving micro-detail and spatial cues. You’ll notice:

• Warmth & Body: The double-triode tubes impart a natural, rounded low-mid richness without ever sounding bloated.
• Transparency & Air: Low distortion (<0.01% at 1kHz/100V RMS) keeps transients crisp and imaging pinpoint-accurate.
• Extended Bandwidth: Effortless treble extension up to 90kHz opens a sense of air and limitless ambience.
• Dynamic Control: With 60dB gain and up to 300V RMS output, the SRM-500T drives even the most demanding electrostatic earspeakers with authority.

Who Is the SRM-500T For?

If you’re an audiophile seeking the sonic character of vacuum tubes combined with STAX’s electrostatic refinement, the SRM-500T is built for you. Ideal pairings include:

• Electrostatic headphone enthusiasts craving both warmth and precision
• Collectors upgrading from solid-state drivers to a hybrid tube solution
• Home-studio professionals requiring ultra-clean detail for critical listening
• Anyone ready to elevate their headphone experience to a reference level

Pros & Cons

• Pros
  • Exceptionally low noise floor with custom dual FET front end
  • Rich, warm tube character without sacrificing clarity
  • Extended DC–90kHz bandwidth delivers unrivalled air and detail
  • Rigid, non-magnetic chassis minimises vibration artefacts
  • Efficient hybrid power supply reduces consumption and heat
• Cons
  • Premium price point reflects high-end components
  • Single RCA and XLR inputs (mutually exclusive) may limit multi-source users

Elevate Your Listening Experience with the SRM-500T

If you’re eager to hear what the STAX SRM-500T Vacuum Tube Driver Unit can do for your electrostatic headphones, our team at The Audio Tailor is ready to help. Explore the full specifications and place your order via the STAX SRM-500T product page, or speak with Gabby, Nathan, Vaughan or Isaac today by calling 1300 308 711 or emailing sales@theaudiotailor.com.au. Your journey to audiophile paradise begins here.