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Experience the pinnacle of audio performance with the Secondhand Stax SRM400s Solid State Driver, now available in excellent condition at Len Wallis Audio.

Pricing available on application which will includes installation and shipping costs to your nominated location

Crafted with precision, the SRM400s features a custom-made low noise DUAL FET installed on both the first and last stages. Each FET is meticulously selected and measured to ensure optimal performance. Drawing inspiration from the high-end SRM-700S model, the SRM-400s inherits its design and manufacturing methods, guaranteeing exceptional audio fidelity.

Enhancing efficiency and sound quality, the SRM-400s boasts a newly designed power transformer with a dedicated winding for the low voltage circuit. This innovative feature not only improves power efficiency but also delivers superior sound quality compared to conventional driver units like the SRM-353X.

Housed in a robust chassis with a hybrid structure, utilizing non-magnetic aluminum, the SRM-400s minimizes environmental noise factors such as vibrations, ensuring pristine audio reproduction. Equipped with RCA and XLR inputs, along with a custom-made concentric dual volume knob and RCA PARALLEL OUT functions, this driver unit offers versatility and convenience.

Committed to quality, all electric components are rigorously selected to enhance both environmental sustainability and performance. The SRM-400s incorporates a complete DC amplifier configuration, eliminating coupling condensers from the signal circuit for unparalleled clarity and fidelity.

From the dynamic low range to the high-resolution sound unique to semiconductor circuits, the SRM-400s delivers a balanced and harmonized audio experience surpassing its predecessor, the SRM-353X. Whether paired with the advanced lambda series or upgrading from entry-level models like the SRS-3100, the SRM-400s caters to both beginners and intermediates, making it an ideal choice for discerning audiophiles.

Unlock the full potential of your audio system with the Secondhand Stax SRM400s Solid State Driver.

Weight 3.4 kg
Dimensions 376 × 195 × 102 mm

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At Len Wallis Audio, whether you’re purchasing in store, over the phone or online through our ecommerce store, we want you to be completely satisfied with your purchase.

Our Refund, Return and Repairs Policy is here to clarify any concerns or questions you might have prior to you making a purchase from us. This way you can be sure of our policy on refunds, returns and repairs and your rights under the Australian Consumer Law.

We also recommend you immediately inspect any goods that you receive from us to ensure you are completely satisfied with the goods, including that the goods are of acceptable quality, and match the description we have provided to you.

If you have any questions about this policy, please contact us at or 02 9427 6755

We require a receipt or proof of purchase.

  • Please do not send your purchase back to the original manufacturer.
  • There are certain situations where only partial refunds are granted (if applicable). For example:
    • Any item not in its original condition, is damaged or missing parts for reasons not due to our error
    • Any item that is returned for reason of change of mind more than 14 days after delivery or purchase from the store.

Consumer Guarantees and Your Rights under the Australian Consumer Law

Refer to our page for more information.

Goods Damaged in Transit.

If any goods arrive damaged, please contact us as soon as possible. Len Wallis Audio will arrange to have the damaged goods returned and either arrange for a replacement of the goods or refund the price to you. Damaged goods must be returned in the condition received by you with all original packaging, accessories and/or manuals.


Refunds will be normally be processed within five (5) days.

Delivery Charges

Where Len Wallis Audio considers the goods to have breached a consumer guarantee, any shipping costs to return the goods to Len Wallis Audio will be at our cost.

Returns and Repairs.

You may visit Len Wallis Audio and a staff member will assist you with any return or repair. This may include inspecting the goods, arranging for the goods to be repaired, or providing you with a replacement.

Goods must be returned within a reasonable time. 

If any goods cannot be easily returned to us due to their size, the fault or because they have been affixed or installed in your premises, please contact us and we will arrange an inspection to assess the goods.

Goods returned for repair will be assessed and/or repaired within a reasonable time. You may be provided with an indicative repair time, which time may vary due to reasons beyond ours or the repairer’s reasonable control, such as part availability and incorrect fault description.

You may be required to pay labour, assessment and/or freight fees, such as where goods are assessed to have been damaged by misuse or accident, or where your rights under the Australian Consumer Law or any manufacturer’s warranty do not apply. We may provide you with an indicative fee, which may vary due to reasons beyond our control.

If any goods that you return are capable of retaining user generated data such as files stored on a hard drive, and songs stored on a portable media player, the replacement or repair of the goods may result in loss of the data. In these circumstances, we recommend you back up data to prevent data loss, and remove sensitive or confidential data, as a party assessing and/or repairing your goods may be required to view data in the course of carrying out the assessment. We will not be responsible for any data loss.

In some circumstances, goods presented for repair may be replaced by refurbished goods of the same type rather than being repaired. Refurbished parts may be used to repair the goods.

Contact Us

Where you have any questions or concerns relating to your Order, please immediately contact us

We understand that sometimes you may simply change your mind about a purchase or have made a wrong selection. In these situations, you have 14 days in which to return your item for a refund, exchange or store credit. If more than 14 days has passed since your purchase we can’t offer you a refund, exchange or store credit.

To be eligible for a return, refund or store credit your item must be in the same condition that you received it. Which is to say, it must be in the original unopened packaging, and in ‘brand new’ saleable condition.

Please note that current Australian Consumer Law does not require us to offer a ‘Change of Mind’ refund. Rather Len Wallis Audio offers 14 day ‘Change of Mind Policy’ in good faith. For more information on consumer rights and guarantees, please visit the Australian Competition and Consumer Commission web site.