iBasso PB5 OSPREY Dual Nutube 6P1 Vacuum Balanced Tubes Portable AmplifieriBasso PB5 OSPREY Dual Nutube 6P1 Vacuum Balanced Tubes Portable Amplifier Pure Analog Magic: Dual NuTube 6P1 Tubes Experience the allure of analog sound with the iBasso PB5 OSPREY. Featuring dual NuTube 6P1 vacuum tubes, this high end portable amplifier delivers rich tones and clear dynamics across the frequency spectrum. Developed by KORG and Noritake, the NuTube technology achieves the warm overtones synonymous with traditional vacuum tube