All of JM AUDIO headphones are guaranteed to be operational and tuned to the customers preference. If any headphone is not tuned as such - the headphone can be returned for a retuning - paid by JM Audio if in the USA back to the original purchasing customer. Original owners in foreign countries can pay for shipping one way to us and we will do one re-tuning freight paid back to customer. We do offer life time re-tunings freight both ways paid by the customer and the re-tuning is fee of charge. Since all products we make are wood and wood has variations and minor imperfections can be expected. We try to avoid such issues through our inspection process and take any imperfections as character of a handmade product but realize some limitations to our inspection process and will take each case of imperfections on a case by case basis. If any headphone headband breaks within in the first year of first ownership or has to be replaced, we do so free of charge once item is shipped to us and we will pay for shipping back to the customer no matter where they are located. We do suggest using Prirateship or Shippo for the cheapest rates for UPS and USPS. Any returns for re-tunings to second parties can be arranged at the second owners expense of shipping both ways, but the re-tuning is performed at no charge.  Refunds are not available on custom tuned headphones. We will strive to achieve the tuning the customer prefers and will recommend ear pads that may not have been included to satisfy further refinement to the original owners at near our cost if the customer needs extra pads or to achieve better sound or performance for comfort. We strive to make our customers happy, and each custom driver is hand selected and matched and guaranteed from defects or failure for one year where by repairs will be made free of charge with shipping sent free back to the customer. We are proud to offer re-tunings and think this is an ideal way for customers to really customize their headphones with us, and we like to know the amps dacs and wire and music types you enjoy. We also would like to know which headphones you like and dislike so we can try to match that particular tuning for your preference. If tastes change some time later, you are entitled to re-tunings free of charge for life as the original owner - shipping to and from is the responsibly of the customer however.