Brand New in Original Packaging

2x International 5591/403B (Matched Pair)

YEN AUDIO Tested and Guaranteed^SM

This auction is for one MATCHED PAIR (2 tubes) of the high quality International 403B vacuum tubes compatible with headphone amps and tube buffers using the 6AK5/EF95/6J1 tube.  Every tube we sell is tested by our Tested and Guaranteed (TAG) program; each tube is tested for defects and measured individually to meet or exceed its original factory specifications before it is carefully  packaged for shipment. If you are looking for a different tube chances are we have it in our extensive inventory, be sure to visit the Yen Audio store to browse our huge selection of vacuum tubes and related accessories including our high quality tube dampers and tube boxes. 

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Compatible with the following equipment:

Little Dot: I+, MkII, MkIII, MkIV, MkIVse

Yaqin: CD2-6J1 tube buffer

DarkVoice: DV332, DV3322

HifiMAN: EF2, EF2A

Grant Fidelity: B-283 Tube Buffer

And many more!

Tested and Guaranteed^SM (TAG):

At Yen Audio we believe you deserve the simple peace of mind of knowing that the tubes you purchase from us will function properly when installed.  Through the Tested and Guaranteed (TAG) program, we have developed a thorough and strict testing procedure to inspect  each tube for defects such as gas leaks, shorts, open filaments and  measure the mutual / trans-conductance level to meet or exceed each  tube's original factory specifications.  We discard any tube that failed any of the aforementioned tests and we do not sell used tubes.  Our calibrated mil-spec Hickok  TV7-B/U and Maxi digital testers ensures a high level of accuracy and reliability.  Each  tube also comes with an unconditional 30 day guarantee; should  you desire to return the tube for any reason (or for no reason at all!); simply return the product to us for a refund of the purchase price or  exchange for another tube; it's your choice!

Shipping and Handling:

Domestic shipping via USPS includes delivery confirmation and full insurance.  International packages under 4 pounds are shipped via USPS International First Class Mail and do not include tracking; International packages over 4 pounds are shipped via USPS International Priority Mail with full tracking and insurance.  Take  advantage of the available combined shipping discounts when you purchase more than one item at a time. Please contact us if you require other  carrier options, we are happy to assist you!

About Yen Audio:

Yen Audio is run by passionate musicians and audiophiles based in sunny Phoenix, Arizona with one of the largest vacuum tube inventories in the American Southwest.  Our simple commitment to our valued customers is to treat you as we like to be treated ourselves and to ONLY stock items we consider good enough for use in our own systems. By combining our extensive expertise in  electronics and tube-based equipment with our comprehensive inventory,  we strive to bring the best value and service experience to our  customers. We like to see our customers happy. If you have any questions or comments please feel free to contact us, we are always happy to hear from you!

Thanks for Looking and Happy Bidding!

Link to our Store: Yen Audio store