preamp to pair with pass xa30.5

Oppo UDP 205 if discs matter to you. Dspeaker X4 if room optimization matters: http://www.dspeaker.com/en/products/anti-mode-x4.shtml

Indeed. And if your disc player also has a volume control you may not even need that passive pre/volume control (provided the DAC in the player is 32 bits internally). In my desktop system I use my computer as a source, into an ODAC usb dac with fixed level (2.1 Volt) output, and then an Emotiva Control Freak volume control, into a Quad 405-2. The Quad has a 0.5 Volt input sensitivity so I have added 16 dB inline attenuators to prevent accidentally blowing up my speakers, and to avoid the inevitable inaccuracies of using an analogue volume control at the low volume end of the range.