Need help in picking a 300w 7channel amp.

You might look at the MC207 from Mcintosh. I can tell you from experience that many companys rate their amps as having more power than they really deliver. The Mc has 200 (4 or 8 ohm)per channel which I realize is 100 shy of your indicated 300.
But McIntosh amps deliver a strong 200 watts that can deliver more on transients than some other amps claim to.
Again I realize the 200 is not 300 but I think you might be suprised if you can get an in home demo arranged.

Going from a 200w to 300w amp isn't going to give you much more volume. Remember, doubling your watts doesn't double your volume.

Take a look at Amplifier Technology Inc (ATI) amps. I picked up an ATI 3007 7 channel amp recently - 300 watts @ 8 ohms. They are the same company that owns Theta now. Built like a tank, tons of power, fully balanced design and sounds great. You can crank this amp and it doesn't run out of steam. 7 monoblock amps in chasis, two big toroidal transformers, high current, 143 lb beast.

I think you can get the ATI for about $4995 new, and I purchased mine slightly used for half of new.

Other recommendation is Earthquake Cinenova 7 channel - 321 watts @ 8 ohms - I think you can get one around $3-4K new.

I highly recommend the ATI - Great amp, great value