What is the best receiver to use with the A90J? Budget up to $2k

for $2K you can get a real nice 5 channel amp and processor...the prices on processors drops fast so many excellent used ones are quite inexpensive...I have separate 2 channel and home theater, but still feel i get much better performance from home theater separates...

So there's this huge argument that says "2-channel audio is the way to go".  If you look at spending $2,000 and have a choice between a 2-channel integrated amp and an AV Receiver, it is very likely that the 2-channel integrated amp is going to sound superior.  That is the entire premise for millercarbon's argument.  If you are going to use this system for 70% or more "music only" listening, this could be the way you want to go.

However, there are problems with the "2-channel only" approach if you are heavy into watching movies.  Whatever source components you have, the entire 5/7 channel source has to be down-mixed into only 2 channels.  This presents problems.

This is a VERY EASY experiment to make. 

1. Pick an action movie that you are very familiar with and watch a 10 minute progression where there is a lot of sound going on.
2.  Go into your Pioneer receiver configuration menu and disable the surround speakers.
3. Re-watch the same 10 minute progression.
4. Go into Pioneer configuration and now disable the center channel.
5. Watch the same progression.

This will show the type of sound you will get when playing movies through a 2-channel only system.  If you are okay with this type of sound, then by all means go with a 2-channel only audio rig.  The compromises are basically the following:

no center channel - Basically you lose a lot of clarity and solidness in the dialogue and anything coming.  Millercarbon's argument that you don't need a center channel is all based on absolutely perfect room acoustics and sitting your butt down EXACTLY at the center point between the left/right speakers.  However, just move to the side 5" and you're whole center channel image is completely lost.  You can try this experiment in your own situation.  This is compounding by the fact that the center channel dialogue is cut by 50% and then sent to each left/right speaker, so if you are off center, that "center channel dialogue" will be quieter and actually harder to hear.

no surround channel - I have had problems on 3-channel systems that do not have actual surround. If you down-mix the surround channels to your left/right speakers, what happens is that the left/right become increased in volume and will have an "echo" type of effect.  The second problem that occurs is that your center channel dialogue becomes extremely difficult to hear/understand because the overall volume of the left/right speaker totally overbears any sound coming out of the center.  You can fix this if you use an HT processor just by enabling the surround speakers (even if nothing is connected).  You will obviously not hear the surround effects, but it gets rid of this problem.  However, the surround speakers actually make the entire sound stage much bigger.  If you disconnect the surround speakers and listen, the whole soundstage becomes smaller since your soundstage is only the front of the room (almost like converting a stereo music song to be played as "mono"). 

Hi OP,
I'm not sure what your trying to accomplish.  It sounds like you just want to update your surround system while you watch TV.  A new AVR would probably have better room correction with the addition of Dolby Atmos. Atmos will require more speakers.  How much two channel music do you listen to?
If you just want better surround for TV with no Atmos, I think I would use your budget to replace your front two or three speakers.  Move your L/R to the sides and create a 7.1 or use them to upgrade your rears.  A lot depends on the size of your room and 5.1 might be plenty.  A couple of subs are nice, too, but your neighbors might disagree. Go used if you can find the right deal.   Hope some of this helps.

Despite the 2-channel bias this site tends to have (me included), I can certainly appreciate the benefits of watching movies on a decent 5.1 system.  Toward that end, and considering your speakers, you could easily get by with a Yamaha RX-A780 AVR you can get from accessories4less.com for only $550 — and, frankly, your speakers don’t warrant spending much more than that anyway IMHO.  It can do 7.2 or ATMOS if you ever decide to go that way, and as your speakers are 90dB efficient it has enough power to drive your system (especially since you have a subwoofer) and will likely sound better doing it than your current Pioneer.  Yamaha also has the distinction of producing the most reliable mass market AVRs so you should be good to go for another 10 years if you so desire. 

If you have the itch to upgrade your system you can look at the RX-A2080 at $1299 (from the same store) and look at the SVS Prime line of speakers for a significant upgrade in that area as well without breaking the bank.  Anyway, hope this helps and best of luck in your search.