Need a receiver for loud CLEAN music.

Not sure for $500 new, you will see any big improvement. Sometimes you can get a deal on a used high power receiver. Or an amazing close out deal.

The 667 is probably a step up in power, and uses discrete amps if you want to stick with Yamaha. But it feels like a small improvement, to me.

Onkyo has been known to put out pretty good power, but I don't know about the last few years.

Harmon Kardon prides themselves on putting out receivers with good power supplies using their so called 'high current design.' And you can get refurb HKs. Don't know how they are for long term quality.

And if you want to save up for a bigger jump in power, there's some nice Emotiva amps. But they require a receiver with pre outs, so you end up close to $1000 when you are done.

Maybe some other people have better ideas in the $500 range.

Onkyo RC-180 has good power. THX Select 2 Plus certified. Nice big power supply. 40lb receiver. Just make sure you keep it well ventilated because it will run hot.

http://www.amazon.com/Onkyo-HT-RC180.../dp/B002L6GEKG

Most AVRs that sell for < $599 have BS power output specs..
If thats your budget then get an AVR with Pre-Outs that way later you can add an out-board component amplifier if you need more watts..

Just my $0.02...

+1

You can find a used Carver with more headroom with the allowable budget... or something else to get more juice through the speakers.

Just remember, everything in your setup makes a system... Speakers should match amp, amp must match pre amp outputs to maximize the benefits.

Usually you look at reviews that do benchmark testing, although most publications these days only really review higher end gear ($800 and over).

One of the easier ways with receivers is to just "weight shopping." For example, a 30lb receiver, based on all the reviews I've seen is probably not going to give you 100W/channel--and if you want to personally verify you can always measure power draw from the wall yourself. A 40lb or 50lb receiver probably will though.

You can look at power consumption in the manual. You can compare a receiver to past receivers that seem comparable that had bench tests.

Some people question the usefulness of all channels driven power ratings, such as Gene over at Audioholics. On the other hand, a $200 receiver with 100x7 rating is pretty much lying. So, I am not sure where that leaves us. Don't buy the cheapest receivers, I guess