Sony 777ES vs Sony 7100 ES Receiver upgrade?

"Sorry Newmanoc, I think you may be mistaken unless you have listened to the Sony 7100ES Receiver."

Well, it is certainly possible that I am. I haven't heard this receiver, and certainly not driving B&W 703's specifically. If you have, then your opinion is far more credible than mine. I only offer my view with such experience as I do have, and with the awareness that going into low ohm loads is beyond that for which Sony receivers are typically well suited.

But if you have not heard this receiver driving the B&W's in question, but only seen pictures of Sony receivers hooked up to B&Ws or read some review citing it was done (a little shy of a true A/B comparision, I'm sure you'll admit), then I would agrue caution is in order before suggesting this is anything remotely like a good idea.

But I think all three of us who have posted thus far are in agreement that the best solution is getting a true multichannel amp and using the current receiver as a processor.

The reason that the 7100es weighs substantially less than your old 777es is because it uses digital amplification as opposed to analog. It still has a massive toroidal transformer but since the digital amplification is something like 90% effecient, it doesn't produce heat like analog amplification does and as such, does not need the massive heat sinks that make up most of the weight in traditional analog receivers.

For what its worth, the 7100es is a lot more powerful than even the 5000es from a couple of years ago thanks to its massive power supply (the old 5000es used switching power supplies and had no toroidal transformer.

With all that said, the 7100es will sound completely different from your 777es as it has a smooth digital sound which is very revealing and clear. Your 777es by comparison will sound more warm in not a touch muddy by comparison. You may find that the digital sound is not for you. Take a listen and see.

Keep the 777ES (its bulletproof) and just get an amp to drive your speakers. I own two older ES receivers and wouldn't trade em for anything. There will always be "Sony bashers" but they don't know the quality put into the ES line which is Sony's "Lexus". If you've got the upgrade bug and can't shake it, let me know if you want to sell the 777. Cheers!