The Onkyo TX-SR705 is the best value right now.
Don't worry about refurb, it's still like brand new, you have a warranty and accessories4less is a very good reputable place.
THX is a certification that means the receiver pass a bunch of tests, plus it is a safe assurance of the performance.
Audyssey MultEQ XT is top of the line, much better than anything else.
And the 705 have preouts for all channels. All your other receivers don't have those.
Very nice feature to add external amps if you wish so in the future.
Read reviews about the 705, and you will see why at only $440, it is a steal and a better receiver than the others, with more features, more power, good sound, etc.
If you passed up on this, you will be missing big time.
Check at other forums what people have to say about this extraordinary receiver, it is mind boggling. It usually retails for $900. It is over 50% off!
All your other choices don't even come close to all the fantastic features of the 705.
Yamaha YPAO does not compare with Audyssey MultEQ XT.
Onkyo 606 only have a lower Audyssey room EQ, does not have THX Select2, no preamps out, etc. The sound quality of the 705 is much better with more power than the 606. Trust me. And read the reviews and the comparisons to your choices, you will understand what I'm saying to you.
That's why I said to you before that if you can stretch your budget by only $90, you will be gaining big time, very big upgrade from all the ones that you mentioned.
The 705 is highly recommended, and at the price, is a no-brainer. Check the Official Onkyo TX-SR705 owner's thread at AVS.
You'll be set for a very long time with this receiver, you'll be glad that you choose it over any Yamaha in your price range, and over the Onkyo 606, big time too.
The 705 is a very sophisticated receiver with a high pedigree, and very good sound quality.
Cheers,
Bob
Note: If you want an inferior receiver for less money, your best bet is the 606 for only $319.99 at accessories4less. Do you want a top performer receiver that is right for you, or do you want one that is from an inferior class? It's your decision, and yours only. I already know mine.
And I agree 100% with the post just above, from jostenmeat.