This workhorse may not the the newest headphone amp but I've owned two and they have been reliable worth amazing sound. Easy to use, good battery life. This one shows signs of wear, the battery compartment lid on one side doesn't hold a well as it did but it's still stable and stays closed. There's a little dent or scratch here or there. Still plenty of life left! Powerful enough to drive my large hifiman planar over ear headphones. Only selling because I've moved to IEMs.
eBay