[Todd smith]

Not even sure what this means, but I have read it is necessary in order to pair it with the denon dvd-2900 for dvd-a and sacd.

[Marcel_V]

Yeh, and even better they are actually 7.1 analog inputs in case you need more channels for a new format. You can switch it to take 5.1 for sacd/dvd-a or 7.1 with the remote.

[Andy_Steb]

I have both the 525 and the 2900, both great units.
Yes, the 525 has 8 channel analog inputs.they can be configured 4 ways.
6 channel direct (5.1 no bass management)
6 channel dvd audio (5.1 and 525 applies bass management)
8 channel direct (7.1 no bass management)
8 channel dvd audio (7.1 and 525 applies bass management)