Integrated for bi-amping with AtmaSphere MA1s

My speakers (Ascendo ZF3s) have separate terminales for each driver.  I am currently using Atmasphere MA1s for the mids and tweets, and using a Pass X1 and Aleph3 for the woofers.  I'm also using a set of old Entec LF20 subwoofers crossed over with a Behringer Ultracurve pro for the really low frequencies.  I would like to replace the X1 and Aleph3 with a more powerful integrated, and am not sure what to use.  I've been away from this hobby for a number of years, but my first instinct when I think low frequencies is Krell.  The S300i looks intriguing, but I've read that it comes from a dark time in Krell's history, and may not be terribly reliable, and not up to the stnadards of low-frequency reproduction Krell is known for. 
Is this a good choice?  What else should I consider?
What about a good class d? There are a few good ones with tons of power and NO NOISE background.. I love um. Run cool...

What's wrong with the Aleph3? That is a good amp, too. Quite a little heater though...

It will push any load, down to  0 (zero) I think. :-)

The Aleph 3 is an awesome amp! I’m just thinking it might not have enough power for the woofers, although it does sound pretty good. I’m hoping to get a bit more dynamic transient response with a bigger amp. I thought it threw a lot of heat until I got the Atmaspheres.
I would consider class D, but I don't really know what's out there.  I'd also like it to have a volume control and a preamp out to feed the subwoofer. 
rouge audio cronus magnum has preamp outputs for biamping and 2 outputs for subwoofers it is tubes 
I like a few different ones, depends on the duty. For bottom to top, Hypex modules, work real well. Mine are from Nord, in the UK, and got wonderful service. There is an option for volume control, rack mount, buffer board, opAmp options. There is a company called VTV on eBay, they have Hypex modules also, state side.

Your running a 2496, Behringer? That will give you 6 lines out with any signal you want for subs or otherwise.
I use them for all my, bass management including servo bass, MB / Bass columns, and standard low rider bass bins (under 36" tall). I use Behringer 12Ks for all my bass work. 450-550 for 4.5K per channel, and bullet proof. They are good to 2 ohm or less.  I think I paid 1400.00 for 3 new amps wit h3 year warr.
Full DSP, on the fly correction, for 6 channels.  2496/12k x 3. I’m a Mac guy so I have tone control to boot.

I mod them and disconnect 2 of the three fans, and put one on a toggle switch. They work perfect and have volume control, LP/HP filter, mono/stereo output. Did I mention 4.5K at 2 ohms and 3K plus at 4 ohms. LOL NO NOISE! Dead quiet, on the floor noise.

Second, my little toggle switch addition, makes for late night, low volume listening, with a flip of a switch, no fan noise, I’ve seldom gotten them warm without the fan, much less with, and with THREE, you’d be DEAF, if they ever got warm, they can really pump it out...VERY low distortion.

HONEST1rouge all so has pharaoh integrated amp class-d pharaoh on the lows  atmasphere on the highs and has subwoofer out puts to

The MA1’s OTL’s would be fast, so you need an amp to blend well with that, and yet have strong bass control, and yet with a good lower mid sound. I don’t think the 30w of the Aleph is the way to go.

If you want an integrated that can have speed good bass control and have good lower mids, Yes the Krell S300i would do, also a Gryphon Diablo 120 would be nice, or even a Pass Labs Int-60.

Cheers George
I've never heard an Ascendo loudspeaker, so I'm just speculating based upon what I've read.  Isn't one of their major design goals a coherence of presentation.  Wouldn't all these different amps, crossovers and subwoofers negatively effect the design goal?  Why not just run it with the MA-1, or if you want to max out, multiple sets of MA-1s.
why not use the Atma-shere MA-1 for the whole thing? in my experience the OTL’s do bass very well probably the best I’ve heard from tubes and much clearer then many SS amps out there. you could get another one for synergy if bi-amping is a must. 5ohm load could be an issue if it dips any lower. 

will say will all those tubes and class A amps I bet your room is toasty
Using the MA-1 for the whole thing will likely not give enough bass output as the speakers have a nominal impedance of 5 ohm. One way to make it work well is to get a set of Paul Speltz’s (anticables) Autoformers ans only hook them up to the bass terminals.

While I found that using autoformers on the full frequency spectrum on my previous 4 ohm speakers (Legacy Focus SE) narrowed the soundstage, decay, and air, I tried using the Autoformers just before the speaker cable one for the woofer section and voila - bass was full, tight, and realistic, while the mids and treble were powered directly by the MA-1 with no Autoformers. I highly suggest this route, and if you don’t have Autoformers to try out, they’re not anywhere as pricey as buying a new amp.

Review from 6 Moons on the Ascendo ZF3s :
"Finally in my opinion these speakers require really powerful amps to drive. It’s not obvious when you check their technical specifications as both sensitivity and impedance seem reasonable but my time with them proved otherwise."

This is the most likely reason to get a good bass mid/bass amp like I mentioned in my 1st post.
Spec’d at 5ohm "nominal" (the ZF3’s could be even lower in spots especially in the bass) and no mention of what degree of -phase angle there is, which could exacerbate any low impedance problems even further.

Cheers George
A lot of the amps, mentioned sound great, for bass.  I bet OP is looking to cool the joint off a bit, and still have plenty left in the tank... Not to mention, NOT break the bank.. I duno, maybe I'm just too studious..
I've heard the MA-1 a few times... I like SS bass.  I like the control, speed, and power.  More than anything, I like the loss of HEATERS in the summer.

The MA-1 is a cooker, but sure sounds good.  I liked them with small planars and line source cabinets.  That's my experience with them.

Thanks for the comments all.  I had been using the MA1s full range, with autoformers, but there was still some edge to the sound and softness to the bass.  Changing to bi-amping improved the bass and took the edge off the midrange.  I suppose all the fussing I'm going through to get them to work together is a sign the Ascendos are not the best match with the Atmaspheres, but they do provide the best sound I've ever had, and, in some ways,  some of the best sound I've ever heard anywhere.  But, of course, I'm always looking to improve.Heat can be an issue.  Most summers, there is a brief time I don't use the system much, but this summer seems worse than most.  I am thinking it might be a good idea to use the Aleph 3 during the hottest months to drive the whole speaker full range.
@honest1 have you tried tube rolling the 6SN7s in the MA-1? I was able to get the near perfect sound signature that I wanted by mixing different tubes, two of which Shuguang black treasures, those two especially emphasized the bass and took away any harshness from the highs. 
Yes, I m now running Sylvanias in the 3 middle positions, GE on the drivers, and RCA on the CCS.  The Sylvanias are good across the spectrum, the RCAs tone down the highs a bit.  I have not tried the Black Treasures, but I did get some rare Blue Glass Treasures (these were prototypes)when the Treasures first came out. 
This reminds me, I haven't been tube shopping in a while.  I should probably buy more NOS tubes before they completely disappear.
I own an older pair of Ascendo model Ms and although the speaker seems to function very well on amps of between 50 and 100 watts, much higher power really allows this speaker to breathe. I am a huge fan of Atmasphere amps but my concerns mirror your experience with this combo. Not a fan of class D but if you restrict this design to the low frequencies this might work well.