AV Receivers

[#1]

Why do AV Receivers not have a powered channel for a sub woofer but have a low level output which requires a powered sub.
I'm browsing around for an AV receiver to replace the one built into my blue-ray player and I have to factor in the extra cost of a powered sub (I already have a passive sub).

[#2]

Often the subwoofer is of magnitudes larger in power than the satellite speakers.
This way, the amp doesn't have to be overdesigned to provide say 50W RMS minimum to 300W RMS maximum with all the power limiting nonsense that would also have to go with it.
Other times the customer just uses the front speakers as a virtual sub (if they are powerful enough) - I'm currently running my 7 channel system as a 2 channel system until I work out which route I'll be taking.

[#3]

I can understand the greater load being put on the system by a sub woofer channel and the effect it could have on the other channels.
I'm currently looking at this unit as I want the unit to ethernet connectivity.
I would also prefer Wi-Fi and Bluetooth but those features appear to mean a higher price and a reduction in overall quality.
This is going to be a tough decision as competition in this area of the market is tight.

[#4]

The Yamaha is a good buy - get it from Richer Sounds with a 5 year warranty though as the HDMI ports on all AV receivers seem to have long term issues.
I picked up a high end RX-V767 with blown HDMI ports for £25 - not a bad bit of kit.
Onkyo customer support is meant to be awful - they had major HDMI issues and fobbed loads of loyal customers off.
Pioneer is a little "low end" these days.
Keep your eyes open on www.hotukdeals.com for bargain receivers - the Yamaha ones are constantly up and down in price.
*Edit - the RX-V675 is currently £299 at Richer Sounds (+£30 for a 5 year warranty)

[#5]

Thanks DomS