Some suggestions for you CCallahan.
Hi CCallahan, Welcome to Audioholics.
Your older receiver, the Denon AVR-3600 was one of the best in his time.
If you want to replace it by a similar quality receiver in today's market, you'll have to aim higher on the Denon line, or from another company.
Your budget is about $600 you are saying.
For that money, you'll have to look at a reconditioned (refurb) model.
There are quite a few around that price. And excellent ones too. See below.
1. The Denon AVR-3808ci would be a good choice, but it is over your buget right now.
2. The Denon AVR-2808ci would also be an excellent choice for you, I'm not sure of the price though, but it should be close to your budget, as this is last year model (the AVR-2809ci is this year model, soon to be replaced by the AVR-3310ci).
3. The Pioneer Elite SC-05 is $700, only $100 more than your budget.
4. The Onkyo TX-SR805 (if you can find it) is about between $400 and $600.
5. The Onkyo TX-SR806 is $600 right now (but it will go down, soon as the TX-NR807 appears).
6. The Onkyo TX-SR875 with it's HQV Reon video processor can be had for $800.
7. The Onkyo TX-SR705 or TX-SR706 are $440 and $500 respectively.
8. The Marantz SR8001 can be had for $700.*
9. The Marantz SR7001 can be had for only $500.*
10. The Marantz SR6001 can be had for only $350.*
11. The Marantz SR6003 can be had for $699 or less (that would be a good choice for you).
12. The Marantz SR5003 is about $500 to $550.
* These 3 Marantz models don't have internal decoders for Dolby trueHD and DTS-HD MA. But this not essential, as your blu-ray player could do the decoding.
--> Places to check for great deals are:
1. Accessories 4 less.
2. 6th Avenue electronics.
3. Audiogon.
4. videogon.
5. New Egg.
6. Vann's Electronics.
7. One Call.
8. J & R Music.
9. ABT Electronics.
10. B & H Photo.
>>> That should point you in the right direction.
And don't feel bad if I did not include any Yamaha and Harman Kardon models.
~ It's just that I run out of time and space.
Cheers,
Bob