SKU: 68652837824

STAX SRM-400S Solid State Driver

Sale price$1125.00 Regular price$1250.00
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Description

STAX SRM-400S Solid State DriverMiddle class semiconductor driver unit is renewed. New DC amplifier which FET are installed in all stages. 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

Middle-class semiconductor driver unit is renewed.
New DC amplifier which FET are installed in all stages.

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 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 enables to improve the power efficiency and achieve 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 is improved. The complete DC amplifier configuration that the signal circuit includes no coupling condensers is one of the biggest traditional features.

SRM-400S takes over the high resolution sound which 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 from beginners to intermediates among the renewed driver unit lineup.

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    Exchange/Return Notes
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    SKU: 68652837824

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    Raven
    Phoenix, US
    ★★★★★ 3
    Great pillows, needs more filler tho!
    Size: King Size Pack of 2, Color: White
    Partner says it's the best thing that's ever happened and has helped his back/shoulder pain tremendously. I personally think it needs to give you more fluff or whatever the filling is. Because the tiny bag that comes btwn the two was not enough! However, still comfy, filling is nice and fluffy like a cloud.
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    Reviewed in the United States on March 25, 2026
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    trent hogan
    Draper, US
    ★★★★★ 5
    Very comfortable
    Size: Queen (1 Count), Color: White, Size: Queen (1 Count), Color: White
    Takes a few minutes to fluff up and inflate after opening. Nice fabric. One side is bamboo and one side is cooling. Looks high quality.
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    Reviewed in the United States on May 23, 2026
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    PublicMe
    Waukegan, US
    ★★★★★ 5
    Really Happy With These Pillows!
    Color: Blue, Size: Queen(2 Pack)-20'*30'
    **Review: Really Happy With These Pillows!** I purchased these pillows and couldn’t be happier! First – they’re cool on *both* sides—finally! I’m not sure why that’s so rare (probably to cut costs), but these actually have cooling material on both sides, and it works really well. Second – the venting around the center helps keep them from getting hot at night. A nice touch that makes a difference for hot sleepers. However, the third feature is the best: the filling. Like many adjustable pillows, you can add or remove the fill, and these come with a small extra bag. The base amount was just right for most people. I had to remove some for my wife but added a bit more to mine. The fill itself is excellent—soft but supportive. You sink into it, but don’t hit bottom. These pillows also have a good weight to them, so they don’t feel cheap. They fluff up great and seem very well made. I followed the recommended dryer run when I first received them and had no odor issues at all. Highly recommend!
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    Reviewed in the United States on August 25, 2025
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    Steve Texas
    Belleville, US
    ★★★★★ 5
    Awesome Pillows
    Color: Blue, Size: King(2 Pack)-20'*36'
    AWESOME, they actually stay cool!!! Extra foam to firm and great instructions how to remove foam and make softer. Fantastic product
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    David Hendrix
    Fort Morgan, US
    ★★★★★ 4
    Very fluffy and comfortable.
    It only stays cool for a few minutes. It is a very comfortable pillow.
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    Reviewed in the United States on December 13, 2025

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