Looking to mod a baby Onkyo DVD Receiver - have schematics

[deniss77]

I have an Onkyo DVD receiver, DR-UN7, which is part of a shelf mini-system that I bought in 2006. While most in hi-fi community would probably frown on this contraption, it can play SACD and DVD-Audio, among most other formats conceivable, and has 5.1-channel surround sound capability.

Shortcoming: while there are pre-outs for center, subwoofer, and surrounds, there is no pre-out for the main fronts (only the speaker-level terminals)! And there are no other outs I could use to get around this problem. The amp is only 16Wpc into 8 Ohms with THD 5% at rated power. This sounds really bad on paper, but in reality, I never heard it distort. Still, I want plenty of headroom to drive my main fronts.

Current set-up: for the main fronts, I use a line-out converter to step the signal down to line-level, then I use Onkyo A-RV401 (integrated amp, 100 Wpc) to drive my main fronts (Paradigm Mini Monitors v.4). For other channels, I use Yamaha DSP-E492 (integrated amp, DSP, 60 Wpc) to drive center (Polk CS2) and rear surrounds (Infinity US-1). It's a budget set-up, which is yielding satisfactory results.

First mod seems simple: I want to either bypass or incorporate a switch to bypass the built-in amp and obtain pre-outs for the main fronts (so that there's no need to use a line-out converter). I have a service manual for this unit. Would anyone be willing to have a look at the schematic with me to make sure I'm on the right track?

Second mod might be tougher, though looking at the schematics, I still believe it is doable. Ultimately, I would like to supply separate pre-amp boxes and use the DR-UN7 DVD Receiver only as Disc Player and Tuner. In other words, I would like to bypass its internal pre-amps but retain its DSP, such as Dolby decoding, DTS, and other nice goodies. Again, would anyone be willing to have a look at the schematics with me and answer specific questions to make sure I'm on the right track?

The schematic says that the built-in power amp is on a separate PC board of its own. The pre-amp and the DSP share a board, but they appear decoupled in the schematics. There is an IC chip at the heart of the pre-amp board, which I believe is designed to do the switching between different inputs (i.e., tuner, dvd) and different listening modes (i.e., 2-ch, 2.1-ch, 5.1-ch, DTS, DVD-Audio, etc). Basically, I need to consult about where the DSP signals end and where the pre-amp begins for each channel. The board seems pretty clear, but I do need someone with more knowledge of schematics.

Much appreciated and sorry for the long-winded first post. :-)