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

You might want to search out one of the discontinued EAD Powermaster amps. They made one that produced about 400 watts per channel into 8 ohms. I think it was eight channels. They come up used occasionally here and should be well within your price range. Very highly rated. Sorry I can't remember the exact model number, 8400 possibly, but it shouldn't be too difficult to track down. One of the best features of the EAD amps was something called dynamic steering. This allowed the amplifier to deliver much higher than rated output to adjacent channels if more power was needed there. Essentially this was a 3200 watt beast that could basically distribute that power to whatever channels needed it.

D-Sonic sells a 7 channel ICE power amp that sends app 500wpc to the front 3 channels and app 250 to the rest. It sells for app $3K. I'm sure Wyred sells a version of this product, too.

Alternatively, (if you have the space and inclination) you can buy 7 high output ICE power monoblocks on your budget. I think Seymour AV (among others) sells this type of amp in this price range - app $1K per.

Specs and prices are guesstimates, but I think they're close.

Good Luck

Marty