The iBasso PB5 Osprey redefines the high-end of mobile, symmetrical tube amplifiers and elevates the analog tube experience to a new level. With its two built-in Nutube 6P1 vacuum tubes, it delivers the sought-after, harmonically rich overtones of traditional triode tubes while simultaneously surpassing conventional vacuum tubes in terms of energy efficiency, size, and performance. The six batteries of the PB5 provide a powerful and clean power supply: two batteries are specifically designated for the Nutubes, while the other four support the secondary amplification, resulting in a captivating and clear sound. Volume control is managed through a high-precision 24-step, 4-part stepped attenuator, which allows for excellent analog control and highlights the amplifier's unique sound characteristics with a minimal channel asymmetry of less than +0.1 dB. With an output power of up to 1700 mW + 1700 mW at 32 ohms, the performance of the PB5 is exceptional. This is made possible by a 6-battery power supply and a transistor current amplifier. A two-stage suspension combined with a cathode input reduces microphonics and interference from mechanical vibrations and impedance minimization. Exclusive components such as the 24-step 4-fold attenuator, the top-notch OPA827 operational amplifier from Texas Instruments, and specially designed film capacitors from iBasso ensure sound reproduction in ultimate analog quality. Overall, the iBasso PB5 Osprey is an advanced, portable tube amplifier that promises an incomparably pure and dynamic sound experience with its innovative Nutube vacuum tubes and carefully selected components.