Stax SRM-400S Headphone Amp (Silver)

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Preorder	A Preorder is an item that has not yet been released. Typically the label will set a projected release date (that is subject to change). If a projected release date is known, we will include this in the description in red. Other Preorders are set to release 'TBA.' This means that release date is yet 'To Be Announced'. The Preorder can be released anywhere between weeks, months or years from its initial announcement.
Backordered	An Out Of Stock item is an item that we normally have available to ship but we are temporarily out of. We do not have a specific date when it will be coming.
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Expected On	When an item is Out Of Stock and we have an estimated date when our stock should arrive, we list that date on our website in the part's description. It is not guaranteed.
Special Order	A Special Order item is an item that we do not stock but can order from the manufacturer. Typical order times are located within the product description.

In Stock

An In Stock item is available to ship normally within 24 business hours.

Preorder

A Preorder is an item that has not yet been released. Typically the label will set a projected release date (that is subject to change). If a projected release date is known, we will include this in the description in red. Other Preorders are set to release 'TBA.' This means that release date is yet 'To Be Announced'. The Preorder can be released anywhere between weeks, months or years from its initial announcement.

Backordered

An Out Of Stock item is an item that we normally have available to ship but we are temporarily out of. We do not have a specific date when it will be coming.

Awaiting Repress

Awaiting repress titles are in the process of being repressed by the label. No ETA is available at this time.

Expected On

When an item is Out Of Stock and we have an estimated date when our stock should arrive, we list that date on our website in the part's description. It is not guaranteed.

Special Order

A Special Order item is an item that we do not stock but can order from the manufacturer. Typical order times are located within the product description.

Description

STAX introduces a new semiconductor driver unit: SRM-400S, the successor model of SRM-353X.

STAX custom-made, low-noise DUAL FET is installed on First Stage. And FET is also installed on Last Stage. The characteristics of right FET and left FET are measured strictly. Selected FET are installed as well as SRM-700S. SRM-400S succeeds to the design and the manufacturing method of the high-end model SRM-700S, the amplifier in which FET are installed in all stages.

In addition to the conventional power transformer for the high-voltage circuit, the newly designed power transformer with the winding for the low voltage circuit is installed in SRM-400S. The low-voltage winding improves the power efficiency and achieves further power saving and better sound quality than the conventional driver units (such as SRM-353X).

The new chassis, which is more rigid than the conventional model, is installed. The chassis has a hybrid structure using a lot of non-magnetic aluminum and further reduces the effect of the environmental noise factors such as vibrations. The inputs are RCA and XLR, the mutual exclusion inputs. The custom-made concentric dual volume knob, which is common to STAX products, and RCA PARALLEL OUT functions are installed same as the conventional driver units. All electric components are strictly selected considering the environment. Also, the sound quality and the performance are improved. The complete DC amplifier configuration includes no coupling condensers, one of the biggest traditional features.

SRM-400S takes over the high-resolution sound that is unique to the semiconductor circuit and dynamic low-range sound reproduction. Simultaneously, the good sound balance is further pursued than SRM-353X. From the low range to the high range, the sound of each range is well harmonized. Not only for the combination with the advanced Lambda series, SRM-400S is also ideal for the upgrading from the entry-level SRS-3100. This is the promising new model which covers everyone from beginners to intermediates among the renewed driver unit lineup.

Technical Specifications

Type	All-stage FET configuration DC amplification driver unit
Frequency response	DC - 90kHz (with one SR-L500 MK2)
Gain	60dB
Harmonic distortion	0.01% or less (1kHz/100Vrms output)
Input impedance	50kO (RCA), 50kOx 2 (XLR)
Maximum output voltage	400Vrms (1kHz)
Bias voltage	DC 580V
Operating temperature / humidity	0 to 35 degrees C / less than 90% (non condensing)
Input terminal	RCA x 1, XLR x 1 (mutual exclusion input)
Output	RCA parallel output
Power consumption	30W
Dimension	195 (W) x 102 (H) x 376 (D) mm (maximum protruding portion included)
Weight	3.4kg