Thanks for all the quick replys. Interestingly, the manual doesn't mention anything about feeding the amp from a pre-amp output on the receiver.
It doesn't say anything about connecting it to speaker outputs either, does it?
The specs do indicate an input impedance of 10,000 ohms. You know a speaker output is looking for around 8 ohms, didn't you? That should have been be a pretty good hint. Add to that the fact that there's no provision for a speaker level input on the amp, either.
I believe this model amp is mostly used for studio work.
You believe rightly, but if used properly it can easily be used for consumer electronics as well. Simply provide it with a line-level signal from a preamp
The other problem I have is that there are no pre-amp outputs on the receiver (Onkyo TXSV525). Any suggestions, or am I going to have to return this pre-amp back to the store I purchased it from?
No real suggestions you're gona like. You simply can't use an external power amp with your receiver. You need one with preamp outputs if that's your plan.
By the way, that Behringer is
NOT a preamp. It's a POWER amp. Perhaps a bit of lurking here might do you some good. A knowledge of the basics and some rudimentary terminology might help you in the future with understanding what you read pertaining to this stuff.
Good luck returning whatever it is you want to return.