Stereo Amp

All, I'm looking for a 2 channel amp and am seeking opinions.

The contenders :

- Parasound JC5
- Pass Labs x250.8 (used unit goes ~6K)
- McIntosh MC452
- Anthem STR (amp only)
- Rotel RB1590

My preamp: Arcam AV860
My speakers : B&W 702s2

=> Before you flame me, I'm fully aware that both the pre-amp and the would-be amp retail for more than the speakers themselves and it's not the logical upgrade path. Let's just put that debate to rest, please. I will likely upgrade the speakers down the road but I'd like the preamp and the amp to remain. So for now, this is what I have to work with

=> What I want to achieve : play the fronts full-range, sub-less, with CLEAN sound, TIGHT and CONTROLED bass. The 702s2 CAN be played as such and sound very good. They do require some fine components up the chain to do so. B&W can be brutal in that regard. 

=> What I have now: as good as it is, the A21 isn't cutting it. sibilence and not enough juice to drive the woofers sub-less. Close but not quite. The JC5, which I've demo-ed with the 702s, does a great job at it and is my runner up as it stands.

=> My other specifics : 
- 80% music / 20% movie (I do have a Velodyne sub to reproduce those earth shaking LFEs)
- room size: 25x15
- music genres: jazz, lounge, some electronics music, pop.

=> I located stores that will demo the MC452, the Anthem STR and the Rotel RB1590 with my same speakers. I've heard the JC5. The only unknown is Pass Labs x250.8, save for the fame: from the reviews alone, it would seem like an easy winner. but I've never heard one. Anyone ?

Thanks in advance!
Don't discount those speakers,  sometimes it's surprising how a move to different electronics can really make a speaker shine.   I think many of today's speakers are so good that they may not really be the weak link in a system and often times are swapped out in a lateral move.  
FYI - There is a review of the STR on Hometheaterreview that briefly compares the JC5.
The STR bridges the power supply.  I went with the Mc452 to drive my Kanta 2's.  Never get above 45 amps, which leaves plenty for headroom!
Soundaholic we sell many amplifiers that are amazing we sell Parasound, Krell, Anthem, Coda.

We just got in the new Krell XD series amplifiers and tbey sound really organic and tube like with great bass omph although the gear is still new there is an unmistakable set of qualities showing through.

All three XD amps are identical other than power.

We are going to compare the Krell to the Str next week.

If you have specific questions you can reach out to us.

Unless you really need alot more juice the new Krell gear is one of the best sounding 2 Channel amps we have ever heard.

Dave and Troy
Audio Doctor NJ Krell, Coda, Anthem, Parasound dealers
I have the Pass 250.8 and it's an amazing amp.It will take total control of your speakers and will give you plenty on bass and bass control. I've been using it with Maggie 3.7i and until recently with a sub. The sub died and I'm amazed at the bass without one. Well recorded jazz sounds live in the room. You won't be sorry with the Pass. 
I’ve heard the McIntosh MC452 paired with the B&W and it sounded amazing, I also knew a lot of people who bought the MC452 and all of them love it. Macs always underrated their amp.
take the demo with the MC452 and Anthem STR and report back your findings.  Happy Listening!
I am looking forward to your shoot-out between the Krell XD and Anthem STR as well.  Happy Listening!
Im in the same boat trying to choose Parasound JC1 or mac 452
for my klipsch RF7II 
What about the Anthem P2, it has more than enough power to drive any speaker that you could buy, it's built like a tank and will run for many years of trouble free service.
personally i’d look hard at the krell amps. i imagine that you could find a Duo priced right then update to HD when you want. I think the Duo will greatly exceed the amps on your list except maybe the Pass which i’ve not heard. krell the company is very energized now. just my opinion
btw a duo 300 for sale $4500 on us audiomart. over half off. think the upgrade is about 1k plus shipping. could be done later. a thought only

Buy an old Counterpoint power amp.  Send it to me to upgrade to the bi-polar transistors.  It will sound fantastic for a lot less dollars than the stuff mentioned here already.  Plus I can do an all out assault if you want to go there.  Even in stock for they sound pretty good.

Happy Listening.

A21 isn’t cutting it. sibilence and not enough juice to drive the woofers sub-less.

The JC5, which I’ve demo-ed with the 702s, does a great job at it and is my runner up as it stands.

I’m betting you demoed those in a different room, in which you shouldn’t compare them.

Every single modern B&W speaker has increased output at 10kHz, including yours. So, experiment with toe-in amounts or even no toe-in.

As for bass, your room is large (3000 cubic feet if only 8ft ceilings). Audioholics describes for that size, the speaker must be able to output 115dB minimum between 31.5Hz to 63Hz at a 4 meter distance, I can gaurentee you that your speakers aren’t able to hit those numbers, even if you fed the max wattage it can handle (300W, even though I doubt it won’t have audible distortion in the bass when fed over 100W). 

So yeah, your speakers are physically incapable of having reference quality bass in your room, so I would suggest crossing over at 40Hz or 60Hz, even though I know you said you don’t want to. 
If you are not listening at reference levels, then maybe you are hearing less bass due to the Equal Loudness Contours, our ears hear less bass at lower volumes, in which tone controls/EQ/DSP will adjust this.
i have your speakers. don’t hear much fizz which i’m very sensitive to. actually there are so many great amps being blown out on agon, audiomart, ebay etc. not to be a snob but you can get into some better amps than you listed that will make your fine speakers sound great. no dog in the fight but i’ve been around way too long. pass and mcintosh just don’t rock my boat but many will disagree. not going to fight that battle. 
whats the true budget and do you head bang? 
you can get something special if you don’t rush it. to fully understand is this part of a home theatre system or are you strictly two channel? 
The anthem may be a possibility as i may have some relevant info to impart. something i heard about. i’ll check if interested.