Hello. Here I offer a classic STAX SRD-7 SB Adaptor/Energiser for Electrostatic Stax Earspeakers. With Twin Normal Bias (230V) outputs. SB stands for Self-Biasing, which means It uses the incoming signal from the Speaker Outputs to create the Biasing Voltage. Therefore, it does not require an AC Mains supply. In Very Good overall condition and Technically sound.  Please read detailed description above and carefully Inspect Photos for the correct assessment of its condition. Notice to Zero Feedback buyers: Due to Time-wasters and attempted Fraudsters, I will cancel any purchase without previous contact and agreement! Notice #2: Questions about "Your Best or Minimum Price" will not be answered. Delivery Costs via Recorded (signed for) Mail: Europe (inc. UK, Switzerland): €24 Elsewhere: €40 Note: Service to España (€18) and Deutschland (€22) will be cheaper, via DHL. Shipping costs mean: Transport cost, tape, packaging materials, etc. Further Information: https://www.ukaudiomart.com/details/649996338-stax-srd-7-sb-adaptor-for-electrostatic-ear-speakers-2x-normal-bias-very-good-condition/ https://www.ukaudiomart.com/userads.php?user_id=61260 https://www.head-fi.org/members/rocksteady65.124498/ https://www.headfonia.com/stax-srd-7/ https://hifivintage.eu/en/headphones/2352-STAX-SRD7.html https://www.head-fi.org/threads/stax-srd-7-transformer-box-question.608983/ https://en.wikipedia.org/wiki/List_of_Stax_products Any questions, feel free to ask. I will accept Bank Transfer in Euros gladly, and in fact I would prefer it whenever possible. It is a free service within the Euro Zone.  Thank you for looking!