I want to use my existing SW (from HTiB Philips 4750) with my Yamaha 863.
I'm thinking about 2 ways to do so -
1. I take the SW-preout from Yamaha and feed it to MP3 direct or Digital port on Philips and then use the audio controls on Philips.
2. I feed the preout to SW direct.
The concepts of 863 and your Philips HTIB are slightly different. In the 863, there are 8 independent signals sent - 7 for speakers and 1 for Sub or what is called the LFE channel.
In the Philips HTIB, ALL the signals are bundled together and sent to the sub. The sub in turn has connectors for the other speakers. That is why in the Philips, the cable from the main unit to the sub carries 15 pins. The sub does the separation of the signals (maybe amplifies them also) and sends them to the respective speakers.
In the 863, the pre out is an analog signal for each channel and a LFE output for two subs. Though there is a digital out, if you use this, you will be completely bypassing the capabilities of the 863 and using your Philips for all decoding and amplification.
Generally an AVR has 2 parts - a pre amplifier, and a power amplifier. The pre amplifier does all the decoding, DAC conversion etc, and the power amplifier increases the amplitude and power the speakers. Unless you use the Philips as a external amplifier, there is not much value in connecting the two.
The Digital (Coaxial) out in 863 is used for recorders, and this will have a very low voltage - in the order of 200 mV. Please check with your Philips specs whether this is enough for it to process. In optical out there is no voltage involved, but most AVRs do NOT have Optical out.
Now my questions are -
1. Can HTiB sense the input coming from Yamaha?
If your Philips has 8 analog inputs sockets (RCA) for each channel, yes it can sense the output coming from the 863.
2. Will the HTiB will decode the line in and route it to SW?
By this I am assuming you are referring to the Digital Out of the 863. Yes it may very well do that, but why use the 863 at all then? The 863 has much better decoding capabilities, and ideally you should connect either speakers to it or a external amplifier. As I said before, a digital signal is unprocessed. For all practical purposes, you can connect your DVD Player or other sources directly to the Philips, and bypass the 863.
3. Is there any power mismatch could happen like preout power is too low or too high for the HTiB?
If you are talking about analog pre out from the Yamaha to the analog input of the Philips, there will be no issues. Generally these follow internationally accepted voltages for such transfer.
The SW is getting a single cable (15pin cable) from HTiB box and then all speakers are connected to it. But it is not clear that which cable pin is carrying LFE for SW. SW is 285 Watts RMS and active one. Frequency response- 30-20K.
As I mentioned before, your cable to the sub is taking signal for all the speakers, and this cannot be separated. In most probability your main unit will have no amplification, and that is done inside the sub. Or the cable could be carrying 5 amplified signals and one KFE signal for the sub.
If you look at the 863 it will have a RCA out for the sub. This carries just the LFE signal, and none of the other signals.
If you want to connect the 863 and the Philips, it can only be done through the main unit, if at all.
Please read pages 17 to 24 of the 863 manual where the connections types and usages are explained.
Cheers