There is a definite warmth of presentation, a fuller lower midrange sets up the YBA’s sonic texture. The sound of the Passion PRE550A is based on proximity and immediacy. What sounds the most beautiful is the instruments and vocals located in the middle of the frequency range. Yet this occurs without limiting everything to just the midrange. The treble has an open, strong character, with plenty of energy corresponding to the higher registers of the vibraphone, drum cymbals, etc.
Several things distinguish the Passion PRE550A from other digital/analogue preamps. It is possible to turn off the digital section when playing an analogue source. The analogue section has three inputs — one balanced (XLR), one unbalanced (RCA), and one video pass-through (RCA). There are two sets of RCA outputs and one set of XLRs.
There is a wide choice of digital inputs — I2 S (RJ45), AES/EBU (XLR), S/PDIF (TosLink, coaxial, BNC), and USB – plus there is a network input (RJ45) that accepts signals from a 10 or 100Mbps network. Built-in Apple AirPort Express support enables the Passion PRE550A to work via a wireless AirPort Express network. It has a direct input for an Apple iPod or iPhone that bypasses the Apple’s internal DAC and uses only the PRE550A DAC. There’s also an S/PDIF output jack, should you want to send a digital signal to another component.
The asynchronous USB 2.0 connection for a computer requires a driver if you’re running Windows, but not with a Mac or Linux computer.