SM2558 Active Stereo Summing Mixer

$259.00 ex. VAT

  • Mix and Match HRK 500 Products!
  • Buy VAT FREE with EU VAT Number
  • NO VAT for Orders from Outside EU
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Product Description

SM2558 | Active Stereo Discrete 10 Inputs 500 Summing Mixer

  • Stereo Summing Mixer in a Single 500 Slot!
  • Adds Warmth, Details, Space and Enhances the Mix
  • 10 Active Summing Inputs in Total
  • Real-Time Monitoring and Recording
  • Flexible Stereo Mix-Bus Routing: L, R, L+R
  • Vintage Console Mode
  • Discrete Class-A British Summing Opamps
  • Discrete Class-A Transformer Drivers
  • Custom HRK Audio Transformers
  • Selected NOS Discrete Components
  • Studio-Grade Texas Instruments Opamps
  • Output Adapter Included
  • Direct Sale – Save on Distributors Fee!

SM2558 | Fully Featured Stereo Summing Mixer

The SM2558 is an Active Stereo Discrete Summing Mixer unit which fits in a single 500 rack space.

The SM2558 has a total of 10 active balanced summing inputs which can be used to mix any music material in the Outside-the-Box Analogue Domain.

The Direct Monitoring feature helps to save the outputs of an audio interface and provides seamless workflow without the latency!

The stereo summing bus section is based on the Discrete Operational Amplifiers made with NOS transistors.

The Outputs of the SM2558 are coupled with custom HRK Transformers powered by Class A Discrete Drivers.

Flexible routing allows to assign summing inputs to channel LEFT, RIGHT or LEFT + RIGHT summing bus.

The Vintage Console Mode adds more harmonics by increasing the saturation of the output transformers.

The SM2558 is a compact, yet fully functional summing mixer, with features which can be found only in very expensive studio mixers!

Direct Sale allows us the keep the price low and passes the saving on the distributor fees to our Customers!

Use the SM2558 with a Simple Audio Interface!

The SM2558 can be used even without the D25 split cable, with a simple two-channel audio interface.

The front panel TRS inputs can be used to process any stereo signal.

Simply connect the inputs and outputs of your interface, run any track or finished the mix with SM2558 and get the analogue warmth of Class A Discrete Circuitry and Output Transformers.

All you need are the standard TRS cables!

Discrete Operational Amplifiers Summing Bus

The analogue summing of all 10 inputs is processed with the Class A Discrete Operational Amplifiers.

The Opamps used in the SM2558 are inspired by the famous British design from the ’70s.

The SM2558 Discrete Opamps are made with selected NOS components.

Vintage Console Mode

The Vintage Console Mode adds the harmonics to the signal by saturating the output transformers, typical for the vintage mixing consoles.

The output transformers are not overdriven by the higher signal level.

Special Class A Discrete, open feedback circuitry is used to power the output transformers.

Such solution ensures the high fidelity of the processed mix, equal signal levels and prevents the digital clipping.

The signal is enriched with even harmonics resulting in enhanced bottom-end, space between the mix elements and vivid sound scene.

The Vintage Console Mode can be engaged by the switch on the front panel.

Direct Monitoring

The Direct Monitoring feature helps to save the outputs of an audio interface.

The Direct Monitoring function allows to edit, listen and process the mix at the same time without the latency.

The MON switch converts the front panel TRS sockets into the Direct Monitoring outputs.

The front panel TRS sockets mirror the signal available on the main rear panel outputs.

You can connect the studio monitors and use all interface outputs for mixing.

No cable switching, just seamless workflow without the latency!

The use of the 500 single slot in a stereo configuration.

It might be counter-intuitive to use a single slot of the 500 rack in stereo mode. Nonetheless, it is absolutely possible and completely safe.

The 500 rack rear panel XLR input connector is nothing more than a straight-wire connection between the XLR socket and the 500 module PCB edge connector. Therefore, it can be easily converted to the output with the included XLR male-to-male adapter.

The picture below shows the arrangement of the rear panel XLR connectors. The XLR male-to-male adapter is included with the SM2558.

NOTE: If your 500 rack has any built-in extra routing features, remember to disable any routing options before the use of SM2558.

Demo Video

User Manual – Read before using the SM2558:

SM2558 User Manual


Brand New, Assembled and Tested.

Every single HRK product is carefully tested with Audio Precision test equipment before the shipping to ensure hassle-free operation.


All Items are dispatched from the European Union within 1-3 working days.

We offer Fast & Free Worldwide UPS shipping with tracking.

FREE delivery is available for orders over the 249USD to EU, USA and Canada.

Total cart value / Delivery cost:

up to 99USD / Delivery Cost – 19.99USD

99 – 148USD / Delivery Cost – 14.99USD

149 – 248USD / Delivery Cost – 9.99USD

over 249USD – FREE Delivery

FREE delivery is available for orders over the 299USD to Australia, New Zeland, Japan and other destinations.

Total cart value / Delivery cost:

up to 148USD / Delivery Cost – 19.99USD

149 – 298USD / Delivery Cost – 14.99USD

over 299USD – FREE Delivery

Please check the shipping cost during the checkout.

Delivery to other WorldWide destinations – 24.99USD

VAT and Customs Fees

For non-business orders from the EU, the VAT will be added at the checkout.

VAT is removed automatically for orders from outside the EU.

No Custom Fees for EU Customers.

Orders from the USA below 800USD are customs tax free.

EU Business Customers

If you have the EU VAT number you can purchase the products available in the Bart HRK Shop with no VAT Tax.

Please enter your EU VAT Number at the checkout and the VAT will be deducted from the Total Payment.

The VAT number is automatically checked in the VIES database.

Non-EU Customers

Customers from outside the EU can purchase the items with no VAT.

Please select the destination country and the VAT will be removed automatically.

If the VAT is not removed, please email customer service via the contact form and custom invoice will be issued.

Orders from the USA below 800USD are customs tax-free.

Payment Options:

You can pay for your order with any Credit Card!

Return Policy

Our return policy is a part of the general Terms & Condition which you have to acknowledge at the checkout.

We stand for fair rules and a win-win approach. We understand that our customers may wish to return the product and we do provide such option. However, because we are a small company we can’t afford to run a grade B outlet shop like big distributors and provide the 30 days return period.

We can’t also scrap every returned unit. We could charge our customers more to offset the cost of the returns, this is what major distributors do. Or we can keep our prices low and hope that our customers will appreciate our policy.

This is why we provide the 7 days test period after receiving the package with the ordered items and if you wish to return the item we will accept the return request, providing that the item is not damaged and we can resell the product with the minimal loss for the company.

If the item is damaged during the transport we will do our best to help you and provide the replacement product.


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